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[fs/lustre-release.git] / lustre / llite / rw.c
index e5890bf..017ec52 100644 (file)
@@ -1,7 +1,7 @@
 /* -*- mode: c; c-basic-offset: 8; indent-tabs-mode: nil; -*-
  * vim:expandtab:shiftwidth=8:tabstop=8:
  *
- * Lustre Lite I/O Page Cache
+ * Lustre Lite I/O page cache routines shared by different kernel revs
  *
  *  Copyright (c) 2001-2003 Cluster File Systems, Inc.
  *
@@ -21,7 +21,9 @@
  *   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  */
 
+#ifndef AUTOCONF_INCLUDED
 #include <linux/config.h>
+#endif
 #include <linux/kernel.h>
 #include <linux/mm.h>
 #include <linux/string.h>
 #include <asm/uaccess.h>
 
 #include <linux/fs.h>
-#if (LINUX_VERSION_CODE > KERNEL_VERSION(2,5,0))
-#include <linux/buffer_head.h>
-#include <linux/mpage.h>
-#include <linux/writeback.h>
-#else
-#include <linux/iobuf.h>
-#endif
 #include <linux/stat.h>
 #include <asm/uaccess.h>
 #include <asm/segment.h>
 
 #define DEBUG_SUBSYSTEM S_LLITE
 
-#include <linux/lustre_mds.h>
-#include <linux/lustre_lite.h>
+//#include <lustre_mdc.h>
+#include <lustre_lite.h>
 #include "llite_internal.h"
 #include <linux/lustre_compat25.h>
 
-/*
- * Remove page from dirty list
- */
-static void __set_page_clean(struct page *page)
-{
-        struct address_space *mapping = page->mapping;
-        struct inode *inode;
-
-        if (!mapping)
-                return;
-
-        PGCACHE_WRLOCK(mapping);
-
-        list_del(&page->list);
-        list_add(&page->list, &mapping->clean_pages);
-
-        /* XXX doesn't inode_lock protect i_state ? */
-        inode = mapping->host;
-        if (list_empty(&mapping->dirty_pages)) {
-                CDEBUG(D_INODE, "inode clean\n");
-                inode->i_state &= ~I_DIRTY_PAGES;
-        }
-
-        PGCACHE_WRUNLOCK(mapping);
-        EXIT;
-}
+#ifndef list_for_each_prev_safe
+#define list_for_each_prev_safe(pos, n, head) \
+        for (pos = (head)->prev, n = pos->prev; pos != (head); \
+                pos = n, n = pos->prev )
+#endif
 
-void set_page_clean(struct page *page)
-{
-        if (PageDirty(page)) {
-                ClearPageDirty(page);
-                __set_page_clean(page);
-        }
-}
+cfs_mem_cache_t *ll_async_page_slab = NULL;
+size_t ll_async_page_slab_size = 0;
 
 /* SYNCHRONOUS I/O to object storage for an inode */
 static int ll_brw(int cmd, struct inode *inode, struct obdo *oa,
@@ -96,334 +65,220 @@ static int ll_brw(int cmd, struct inode *inode, struct obdo *oa,
 {
         struct ll_inode_info *lli = ll_i2info(inode);
         struct lov_stripe_md *lsm = lli->lli_smd;
+        struct obd_info oinfo = { { { 0 } } };
         struct brw_page pg;
-        int rc;
+        int opc, rc;
         ENTRY;
 
         pg.pg = page;
-        pg.off = ((obd_off)page->index) << PAGE_SHIFT;
+        pg.off = ((obd_off)page->index) << CFS_PAGE_SHIFT;
 
-        if (cmd == OBD_BRW_WRITE && (pg.off + PAGE_SIZE > inode->i_size))
-                pg.count = inode->i_size % PAGE_SIZE;
+        if ((cmd & OBD_BRW_WRITE) && (pg.off+CFS_PAGE_SIZE>i_size_read(inode)))
+                pg.count = i_size_read(inode) % CFS_PAGE_SIZE;
         else
-                pg.count = PAGE_SIZE;
+                pg.count = CFS_PAGE_SIZE;
 
-        CDEBUG(D_PAGE, "%s %d bytes ino %lu at "LPU64"/"LPX64"\n",
-               cmd & OBD_BRW_WRITE ? "write" : "read", pg.count, inode->i_ino,
-               pg.off, pg.off);
+        LL_CDEBUG_PAGE(D_PAGE, page, "%s %d bytes ino %lu at "LPU64"/"LPX64"\n",
+                       cmd & OBD_BRW_WRITE ? "write" : "read", pg.count,
+                       inode->i_ino, pg.off, pg.off);
         if (pg.count == 0) {
                 CERROR("ZERO COUNT: ino %lu: size %p:%Lu(%p:%Lu) idx %lu off "
-                       LPU64"\n",
-                       inode->i_ino, inode, inode->i_size, page->mapping->host,
-                       page->mapping->host->i_size, page->index, pg.off);
+                       LPU64"\n", inode->i_ino, inode, i_size_read(inode),
+                       page->mapping->host, i_size_read(page->mapping->host),
+                       page->index, pg.off);
         }
 
         pg.flag = flags;
 
-        if (cmd == OBD_BRW_WRITE)
-                lprocfs_counter_add(ll_i2sbi(inode)->ll_stats,
-                                    LPROC_LL_BRW_WRITE, pg.count);
+        if (cmd & OBD_BRW_WRITE)
+                ll_stats_ops_tally(ll_i2sbi(inode), LPROC_LL_BRW_WRITE,
+                                   pg.count);
         else
-                lprocfs_counter_add(ll_i2sbi(inode)->ll_stats,
-                                    LPROC_LL_BRW_READ, pg.count);
-        rc = obd_brw(cmd, ll_i2obdconn(inode), oa, lsm, 1, &pg, NULL);
-        if (rc != 0 && rc != -EIO)
+                ll_stats_ops_tally(ll_i2sbi(inode), LPROC_LL_BRW_READ,
+                                   pg.count);
+        oinfo.oi_oa = oa;
+        oinfo.oi_md = lsm;
+        /* NB partial write, so we might not have CAPA_OPC_OSS_READ capa */
+        opc = cmd & OBD_BRW_WRITE ? CAPA_OPC_OSS_WRITE : CAPA_OPC_OSS_RW;
+        oinfo.oi_capa = ll_osscapa_get(inode, opc);
+        rc = obd_brw(cmd, ll_i2dtexp(inode), &oinfo, 1, &pg, NULL);
+        capa_put(oinfo.oi_capa);
+        if (rc == 0)
+                obdo_to_inode(inode, oa, OBD_MD_FLBLOCKS);
+        else if (rc != -EIO)
                 CERROR("error from obd_brw: rc = %d\n", rc);
-
         RETURN(rc);
 }
 
-/*
- * we were asked to read a single page but we're going to try and read a batch
- * of pages all at once.  this vaguely simulates 2.5's readpages.
- */
-static int ll_readpage(struct file *file, struct page *first_page)
+/* this isn't where truncate starts.   roughly:
+ * sys_truncate->ll_setattr_raw->vmtruncate->ll_truncate. setattr_raw grabs
+ * DLM lock on [size, EOF], i_mutex, ->lli_size_sem, and WRITE_I_ALLOC_SEM to
+ * avoid races.
+ *
+ * must be called under ->lli_size_sem */
+void ll_truncate(struct inode *inode)
 {
-        struct inode *inode = first_page->mapping->host;
         struct ll_inode_info *lli = ll_i2info(inode);
-        struct page *page = first_page;
-        struct list_head *pos;
-        struct brw_page *pgs;
-        struct obdo *oa;
-        unsigned long end_index, extent_end = 0;
-        struct ptlrpc_request_set *set;
-        int npgs = 0, rc = 0, max_pages;
+        struct obd_info oinfo = { { { 0 } } };
+        struct ost_lvb lvb;
+        struct obdo oa;
+        int rc;
         ENTRY;
+        CDEBUG(D_VFSTRACE, "VFS Op:inode=%lu/%u(%p) to %Lu=%#Lx\n",inode->i_ino,
+               inode->i_generation, inode, i_size_read(inode),
+               i_size_read(inode));
 
-        LASSERT(PageLocked(page));
-        LASSERT(!PageUptodate(page));
-        CDEBUG(D_VFSTRACE, "VFS Op:inode=%lu/%u(%p),offset="LPX64"\n",
-               inode->i_ino, inode->i_generation, inode,
-               (((obd_off)page->index) << PAGE_SHIFT));
-        LASSERT(atomic_read(&file->f_dentry->d_inode->i_count) > 0);
-
-        if (inode->i_size <= ((obd_off)page->index) << PAGE_SHIFT) {
-                CERROR("reading beyond EOF\n");
-                memset(kmap(page), 0, PAGE_SIZE);
-                kunmap(page);
-                SetPageUptodate(page);
-                unlock_page(page);
-                RETURN(rc);
+        ll_stats_ops_tally(ll_i2sbi(inode), LPROC_LL_TRUNC, 1);
+        if (lli->lli_size_sem_owner != current) {
+                EXIT;
+                return;
         }
 
-        /* try to read the file's preferred block size in a one-er */
-        end_index = first_page->index +
-                (inode->i_blksize >> PAGE_CACHE_SHIFT);
-        if (end_index > (inode->i_size >> PAGE_CACHE_SHIFT))
-                end_index = inode->i_size >> PAGE_CACHE_SHIFT;
-
-        max_pages = ((end_index - first_page->index) << PAGE_CACHE_SHIFT) >>
-                PAGE_SHIFT;
-        pgs = kmalloc(max_pages * sizeof(*pgs), GFP_USER);
-        if (pgs == NULL)
-                RETURN(-ENOMEM);
-
-        /*
-         * find how far we're allowed to read under the extent ll_file_read
-         * is passing us..
-         */
-        spin_lock(&lli->lli_read_extent_lock);
-        list_for_each(pos, &lli->lli_read_extents) {
-                struct ll_read_extent *rextent;
-                rextent = list_entry(pos, struct ll_read_extent, re_lli_item);
-                if (rextent->re_task != current)
-                        continue;
-
-                if (rextent->re_extent.end + PAGE_SIZE < rextent->re_extent.end)
-                        /* extent wrapping */
-                        extent_end = ~0;
-                else {
-                        extent_end = (rextent->re_extent.end + PAGE_SIZE)
-                                                        << PAGE_CACHE_SHIFT;
-                        /* 32bit indexes, 64bit extents.. */
-                        if (((u64)extent_end >> PAGE_CACHE_SHIFT) <
-                                        rextent->re_extent.end)
-                                extent_end = ~0;
-                }
-                break;
+        if (!lli->lli_smd) {
+                CDEBUG(D_INODE, "truncate on inode %lu with no objects\n",
+                       inode->i_ino);
+                GOTO(out_unlock, 0);
         }
-        spin_unlock(&lli->lli_read_extent_lock);
-
-        if (extent_end == 0) {
-                static long next_print;
-                if (time_after(jiffies, next_print)) {
-                        next_print = jiffies + 30 * HZ;
-                        CDEBUG(D_INODE, "mmap readpage - check locks\n");
-                }
-                end_index = page->index + 1;
-        } else if (extent_end < end_index)
-                end_index = extent_end;
-
-        /* to balance the find_get_page ref the other pages get that is
-         * decrefed on teardown.. */
-        page_cache_get(page);
-        do {
-                unsigned long index ;
-
-                pgs[npgs].pg = page;
-                pgs[npgs].off = ((obd_off)page->index) << PAGE_CACHE_SHIFT;
-                pgs[npgs].flag = 0;
-                pgs[npgs].count = PAGE_SIZE;
-                /* XXX Workaround for BA OSTs returning short reads at EOF.
-                 * The linux OST will return the full page, zero-filled at the
-                 * end, which will just overwrite the data we set here.  Bug
-                 * 593 relates to fixing this properly.
-                 */
-                if (inode->i_size < pgs[npgs].off + PAGE_SIZE) {
-                        int count = inode->i_size - pgs[npgs].off;
-                        void *addr = kmap(page);
-                        pgs[npgs].count = count;
-                        //POISON(addr, 0x7c, count);
-                        memset(addr + count, 0, PAGE_SIZE - count);
-                        kunmap(page);
-                }
 
-                npgs++;
-                if (npgs == max_pages)
-                        break;
+        LASSERT(atomic_read(&lli->lli_size_sem.count) <= 0);
+
+        /* XXX I'm pretty sure this is a hack to paper over a more fundamental
+         * race condition. */
+        lov_stripe_lock(lli->lli_smd);
+        inode_init_lvb(inode, &lvb);
+        obd_merge_lvb(ll_i2dtexp(inode), lli->lli_smd, &lvb, 0);
+        if (lvb.lvb_size == i_size_read(inode)) {
+                CDEBUG(D_VFSTRACE, "skipping punch for obj "LPX64", %Lu=%#Lx\n",
+                       lli->lli_smd->lsm_object_id, i_size_read(inode),
+                       i_size_read(inode));
+                lov_stripe_unlock(lli->lli_smd);
+                GOTO(out_unlock, 0);
+        }
 
-                /*
-                 * find pages ahead of us that we can read in.
-                 * grab_cache_page waits on pages that are locked so
-                 * we first try find_get_page, which doesn't.  this stops
-                 * the worst case behaviour of racing threads waiting on
-                 * each other, but doesn't remove it entirely.
-                 */
-                for (index = page->index + 1, page = NULL;
-                     page == NULL && index < end_index; index++) {
-
-                        /* see if the page already exists and needs updating */
-                        page = find_get_page(inode->i_mapping, index);
-                        if (page) {
-                                if (Page_Uptodate(page) || TryLockPage(page))
-                                        goto out_release;
-                                if (!page->mapping || Page_Uptodate(page))
-                                        goto out_unlock;
-                        } else {
-                                /* ok, we have to create it.. */
-                                page = grab_cache_page(inode->i_mapping, index);
-                                if (page == NULL)
-                                        continue;
-                                if (Page_Uptodate(page))
-                                        goto out_unlock;
+        obd_adjust_kms(ll_i2dtexp(inode), lli->lli_smd, i_size_read(inode), 1);
+        lov_stripe_unlock(lli->lli_smd);
+
+        if (unlikely((ll_i2sbi(inode)->ll_flags & LL_SBI_CHECKSUM) &&
+                     (i_size_read(inode) & ~CFS_PAGE_MASK))) {
+                /* If the truncate leaves behind a partial page, update its
+                 * checksum. */
+                struct page *page = find_get_page(inode->i_mapping,
+                                                  i_size_read(inode) >>
+                                                  CFS_PAGE_SHIFT);
+                if (page != NULL) {
+                        struct ll_async_page *llap = llap_cast_private(page);
+                        if (llap != NULL) {
+                                llap->llap_checksum =
+                                        crc32_le(0, kmap(page), CFS_PAGE_SIZE);
+                                kunmap(page);
                         }
-
-                        break;
-
-                out_unlock:
-                        unlock_page(page);
-                out_release:
                         page_cache_release(page);
-                        page = NULL;
                 }
-
-        } while (page);
-
-        if ((oa = obdo_alloc()) == NULL) {
-                CERROR("ENOMEM allocing obdo\n");
-                rc = -ENOMEM;
-        } else if ((set = ptlrpc_prep_set()) == NULL) {
-                CERROR("ENOMEM allocing request set\n");
-                obdo_free(oa);
-                rc = -ENOMEM;
-        } else {
-                struct ll_file_data *fd = file->private_data;
-
-                oa->o_id = lli->lli_smd->lsm_object_id;
-                memcpy(obdo_handle(oa), &fd->fd_ost_och.och_fh,
-                       sizeof(fd->fd_ost_och.och_fh));
-                oa->o_valid = OBD_MD_FLID | OBD_MD_FLHANDLE;
-                obdo_from_inode(oa, inode, OBD_MD_FLTYPE | OBD_MD_FLATIME);
-
-                rc = obd_brw_async(OBD_BRW_READ, ll_i2obdconn(inode), oa,
-                                   ll_i2info(inode)->lli_smd, npgs, pgs,
-                                   set, NULL);
-                if (rc == 0)
-                        rc = ptlrpc_set_wait(set);
-                ptlrpc_set_destroy(set);
-                if (rc == 0)
-                        obdo_refresh_inode(inode, oa, oa->o_valid);
-                if (rc && rc != -EIO)
-                        CERROR("error from obd_brw_async: rc = %d\n", rc);
-                obdo_free(oa);
-        }
-
-        while (npgs-- > 0) {
-                page = pgs[npgs].pg;
-
-                if (rc == 0)
-                        SetPageUptodate(page);
-                unlock_page(page);
-                page_cache_release(page);
         }
 
-        kfree(pgs);
-        RETURN(rc);
-} /* ll_readpage */
+        CDEBUG(D_INFO, "calling punch for "LPX64" (new size %Lu=%#Lx)\n",
+               lli->lli_smd->lsm_object_id, i_size_read(inode), i_size_read(inode));
 
-/* this isn't where truncate starts.   roughly:
- * sys_truncate->ll_setattr_raw->vmtruncate->ll_truncate
- * we grab the lock back in setattr_raw to avoid races. */
-void ll_truncate(struct inode *inode)
-{
-        struct lov_stripe_md *lsm = ll_i2info(inode)->lli_smd;
-        struct obdo oa;
-        int err;
-        ENTRY;
-        CDEBUG(D_VFSTRACE, "VFS Op:inode=%lu/%u(%p)\n", inode->i_ino,
-               inode->i_generation, inode);
+        oinfo.oi_md = lli->lli_smd;
+        oinfo.oi_policy.l_extent.start = i_size_read(inode);
+        oinfo.oi_policy.l_extent.end = OBD_OBJECT_EOF;
+        oinfo.oi_oa = &oa;
+        oa.o_id = lli->lli_smd->lsm_object_id;
+        oa.o_gr = lli->lli_smd->lsm_object_gr;
+        oa.o_valid = OBD_MD_FLID | OBD_MD_FLGROUP;
 
-        /* object not yet allocated */
-        if (!lsm) {
-                CERROR("truncate on inode %lu with no objects\n", inode->i_ino);
-                EXIT;
-                return;
-        }
+        obdo_from_inode(&oa, inode, OBD_MD_FLTYPE | OBD_MD_FLMODE |
+                        OBD_MD_FLATIME | OBD_MD_FLMTIME | OBD_MD_FLCTIME |
+                        OBD_MD_FLFID | OBD_MD_FLGENER);
 
-        /* vmtruncate will just throw away our dirty pages, make sure
-         * we don't think they're still dirty, being careful to round
-         * i_size to the first whole page that was tossed */
-        err = ll_clear_dirty_pages(ll_i2obdconn(inode), lsm,
-                        (inode->i_size + PAGE_CACHE_SIZE-1) >> PAGE_CACHE_SHIFT,
-                        ~0);
+        ll_inode_size_unlock(inode, 0);
 
-        oa.o_id = lsm->lsm_object_id;
-        oa.o_valid = OBD_MD_FLID;
-        obdo_from_inode(&oa, inode, OBD_MD_FLTYPE|OBD_MD_FLMODE|OBD_MD_FLATIME|
-                                    OBD_MD_FLMTIME | OBD_MD_FLCTIME);
-
-        CDEBUG(D_INFO, "calling punch for "LPX64" (all bytes after %Lu)\n",
-               oa.o_id, inode->i_size);
-
-        /* truncate == punch from new size to absolute end of file */
-        err = obd_punch(ll_i2obdconn(inode), &oa, lsm, inode->i_size,
-                        OBD_OBJECT_EOF, NULL);
-        if (err)
-                CERROR("obd_truncate fails (%d) ino %lu\n", err, inode->i_ino);
+        oinfo.oi_capa = ll_osscapa_get(inode, CAPA_OPC_OSS_TRUNC);
+        rc = obd_punch_rqset(ll_i2dtexp(inode), &oinfo, NULL);
+        ll_truncate_free_capa(oinfo.oi_capa);
+        if (rc)
+                CERROR("obd_truncate fails (%d) ino %lu\n", rc, inode->i_ino);
         else
                 obdo_to_inode(inode, &oa, OBD_MD_FLSIZE | OBD_MD_FLBLOCKS |
-                                          OBD_MD_FLATIME | OBD_MD_FLMTIME |
-                                          OBD_MD_FLCTIME);
-
+                              OBD_MD_FLATIME | OBD_MD_FLMTIME | OBD_MD_FLCTIME);
         EXIT;
         return;
-} /* ll_truncate */
 
-//#if (LINUX_VERSION_CODE < KERNEL_VERSION(2,5,0))
+ out_unlock:
+        ll_inode_size_unlock(inode, 0);
+} /* ll_truncate */
 
-static int ll_prepare_write(struct file *file, struct page *page, unsigned from,
-                            unsigned to)
+int ll_prepare_write(struct file *file, struct page *page, unsigned from,
+                     unsigned to)
 {
         struct inode *inode = page->mapping->host;
         struct ll_inode_info *lli = ll_i2info(inode);
-        struct ll_file_data *fd = file->private_data;
         struct lov_stripe_md *lsm = lli->lli_smd;
-        obd_off offset = ((obd_off)page->index) << PAGE_SHIFT;
-        struct brw_page pg;
+        obd_off offset = ((obd_off)page->index) << CFS_PAGE_SHIFT;
+        struct obd_info oinfo = { { { 0 } } };
+        struct brw_page pga;
         struct obdo oa;
+        struct ost_lvb lvb;
         int rc = 0;
         ENTRY;
 
-        if (!PageLocked(page))
-                LBUG();
-
-        if (PageUptodate(page))
-                RETURN(0);
-
-        //POISON(addr + from, 0xca, to - from);
+        LASSERT(PageLocked(page));
+        (void)llap_cast_private(page); /* assertion */
 
         /* Check to see if we should return -EIO right away */
-        pg.pg = page;
-        pg.off = offset;
-        pg.count = PAGE_SIZE;
-        pg.flag = 0;
-        rc = obd_brw(OBD_BRW_CHECK, ll_i2obdconn(inode), NULL, lsm, 1,&pg,NULL);
+        pga.pg = page;
+        pga.off = offset;
+        pga.count = CFS_PAGE_SIZE;
+        pga.flag = 0;
+
+        oa.o_mode = inode->i_mode;
+        oa.o_id = lsm->lsm_object_id;
+        oa.o_gr = lsm->lsm_object_gr;
+        oa.o_valid = OBD_MD_FLID | OBD_MD_FLMODE | 
+                     OBD_MD_FLTYPE | OBD_MD_FLGROUP;
+        obdo_from_inode(&oa, inode, OBD_MD_FLFID | OBD_MD_FLGENER);
+
+        oinfo.oi_oa = &oa;
+        oinfo.oi_md = lsm;
+        rc = obd_brw(OBD_BRW_CHECK, ll_i2dtexp(inode), &oinfo, 1, &pga, NULL);
         if (rc)
                 RETURN(rc);
 
+        if (PageUptodate(page)) {
+                LL_CDEBUG_PAGE(D_PAGE, page, "uptodate\n");
+                RETURN(0);
+        }
+
         /* We're completely overwriting an existing page, so _don't_ set it up
          * to date until commit_write */
-        if (from == 0 && to == PAGE_SIZE)
+        if (from == 0 && to == CFS_PAGE_SIZE) {
+                LL_CDEBUG_PAGE(D_PAGE, page, "full page write\n");
+                POISON_PAGE(page, 0x11);
                 RETURN(0);
+        }
 
-        /* If are writing to a new page, no need to read old data.
-         * the extent locking and getattr procedures in ll_file_write have
-         * guaranteed that i_size is stable enough for our zeroing needs */
-        if (inode->i_size <= offset) {
-                memset(kmap(page), 0, PAGE_SIZE);
+        /* If are writing to a new page, no need to read old data.  The extent
+         * locking will have updated the KMS, and for our purposes here we can
+         * treat it like i_size. */
+        lov_stripe_lock(lsm);
+        inode_init_lvb(inode, &lvb);
+        obd_merge_lvb(ll_i2dtexp(inode), lsm, &lvb, 1);
+        lov_stripe_unlock(lsm);
+        if (lvb.lvb_size <= offset) {
+                LL_CDEBUG_PAGE(D_PAGE, page, "kms "LPU64" <= offset "LPU64"\n",
+                               lvb.lvb_size, offset);
+                memset(kmap(page), 0, CFS_PAGE_SIZE);
                 kunmap(page);
                 GOTO(prepare_done, rc = 0);
         }
 
-        oa.o_id = lsm->lsm_object_id;
-        oa.o_mode = inode->i_mode;
-        memcpy(obdo_handle(&oa), &fd->fd_ost_och.och_fh,
-               sizeof(fd->fd_ost_och.och_fh));
-        oa.o_valid = OBD_MD_FLID |OBD_MD_FLMODE |OBD_MD_FLTYPE |OBD_MD_FLHANDLE;
-
+        /* XXX could be an async ocp read.. read-ahead? */
         rc = ll_brw(OBD_BRW_READ, inode, &oa, page, 0);
-        if (rc == 0)
+        if (rc == 0) {
+                /* bug 1598: don't clobber blksize */
+                oa.o_valid &= ~(OBD_MD_FLSIZE | OBD_MD_FLBLKSZ);
                 obdo_refresh_inode(inode, &oa, oa.o_valid);
+        }
 
         EXIT;
  prepare_done:
@@ -433,170 +288,486 @@ static int ll_prepare_write(struct file *file, struct page *page, unsigned from,
         return rc;
 }
 
-/*
- * background file writeback.  This is called regularly from kupdated to write
- * dirty data, from kswapd when memory is low, and from filemap_fdatasync when
- * super blocks or inodes are synced..
+static int ll_ap_make_ready(void *data, int cmd)
+{
+        struct ll_async_page *llap;
+        struct page *page;
+        ENTRY;
+
+        llap = LLAP_FROM_COOKIE(data);
+        page = llap->llap_page;
+
+        LASSERTF(!(cmd & OBD_BRW_READ), "cmd %x page %p ino %lu index %lu\n", cmd, page,
+                 page->mapping->host->i_ino, page->index);
+
+        /* we're trying to write, but the page is locked.. come back later */
+        if (TryLockPage(page))
+                RETURN(-EAGAIN);
+
+        LASSERT(!PageWriteback(page));
+
+        /* if we left PageDirty we might get another writepage call
+         * in the future.  list walkers are bright enough
+         * to check page dirty so we can leave it on whatever list
+         * its on.  XXX also, we're called with the cli list so if
+         * we got the page cache list we'd create a lock inversion
+         * with the removepage path which gets the page lock then the
+         * cli lock */
+        LASSERTF(!PageWriteback(page),"cmd %x page %p ino %lu index %lu\n", cmd, page,
+                 page->mapping->host->i_ino, page->index);
+        clear_page_dirty_for_io(page);
+
+        /* This actually clears the dirty bit in the radix tree.*/
+        set_page_writeback(page);
+
+        LL_CDEBUG_PAGE(D_PAGE, page, "made ready\n");
+        page_cache_get(page);
+
+        RETURN(0);
+}
+
+/* We have two reasons for giving llite the opportunity to change the
+ * write length of a given queued page as it builds the RPC containing
+ * the page:
  *
- * obd_brw errors down in _batch_writepage are ignored, so pages are always
- * unlocked.  Also, there is nobody to return an error code to from here - the
- * application may not even be running anymore.
+ * 1) Further extending writes may have landed in the page cache
+ *    since a partial write first queued this page requiring us
+ *    to write more from the page cache.  (No further races are possible, since
+ *    by the time this is called, the page is locked.)
+ * 2) We might have raced with truncate and want to avoid performing
+ *    write RPCs that are just going to be thrown away by the
+ *    truncate's punch on the storage targets.
  *
- * this should be async so that things like kswapd can have a chance to
- * free some more pages that our allocating writeback may need, but it isn't
- * yet.
+ * The kms serves these purposes as it is set at both truncate and extending
+ * writes.
  */
-#if (LINUX_VERSION_CODE < KERNEL_VERSION(2,5,0))
-static unsigned long ll_local_cache_dirty_pages;
-static unsigned long ll_max_dirty_pages = 20 * 1024 * 1024 / PAGE_SIZE;
+static int ll_ap_refresh_count(void *data, int cmd)
+{
+        struct ll_inode_info *lli;
+        struct ll_async_page *llap;
+        struct lov_stripe_md *lsm;
+        struct page *page;
+        struct inode *inode;
+        struct ost_lvb lvb;
+        __u64 kms;
+        ENTRY;
 
-static spinlock_t ll_local_cache_page_count_lock = SPIN_LOCK_UNLOCKED;
+        /* readpage queues with _COUNT_STABLE, shouldn't get here. */
+        LASSERT(cmd != OBD_BRW_READ);
 
-int ll_rd_dirty_pages(char *page, char **start, off_t off, int count, int *eof,
-                      void *data)
-{
-        unsigned long dirty_count;
-        spin_lock(&ll_local_cache_page_count_lock);
-        dirty_count = ll_local_cache_dirty_pages;
-        spin_unlock(&ll_local_cache_page_count_lock);
-        return snprintf(page, count, "%lu\n", dirty_count);
+        llap = LLAP_FROM_COOKIE(data);
+        page = llap->llap_page;
+        inode = page->mapping->host;
+        lli = ll_i2info(inode);
+        lsm = lli->lli_smd;
+
+        lov_stripe_lock(lsm);
+        inode_init_lvb(inode, &lvb);
+        obd_merge_lvb(ll_i2dtexp(inode), lsm, &lvb, 1);
+        kms = lvb.lvb_size;
+        lov_stripe_unlock(lsm);
+
+        /* catch race with truncate */
+        if (((__u64)page->index << CFS_PAGE_SHIFT) >= kms)
+                return 0;
+
+        /* catch sub-page write at end of file */
+        if (((__u64)page->index << CFS_PAGE_SHIFT) + CFS_PAGE_SIZE > kms)
+                return kms % CFS_PAGE_SIZE;
+
+        return CFS_PAGE_SIZE;
 }
 
-int ll_rd_max_dirty_pages(char *page, char **start, off_t off, int count,
-                          int *eof, void *data)
+void ll_inode_fill_obdo(struct inode *inode, int cmd, struct obdo *oa)
 {
-        unsigned long max_dirty;
-        spin_lock(&ll_local_cache_page_count_lock);
-        max_dirty = ll_max_dirty_pages;
-        spin_unlock(&ll_local_cache_page_count_lock);
-        return snprintf(page, count, "%lu\n", max_dirty);
+        struct lov_stripe_md *lsm;
+        obd_flag valid_flags;
+
+        lsm = ll_i2info(inode)->lli_smd;
+
+        oa->o_id = lsm->lsm_object_id;
+        oa->o_gr = lsm->lsm_object_gr;
+        oa->o_valid = OBD_MD_FLID | OBD_MD_FLGROUP;
+        valid_flags = OBD_MD_FLTYPE | OBD_MD_FLATIME;
+        if (cmd & OBD_BRW_WRITE) {
+                oa->o_valid |= OBD_MD_FLEPOCH;
+                oa->o_easize = ll_i2info(inode)->lli_ioepoch;
+
+                valid_flags |= OBD_MD_FLMTIME | OBD_MD_FLCTIME |
+                        OBD_MD_FLUID | OBD_MD_FLGID |
+                        OBD_MD_FLFID | OBD_MD_FLGENER;
+        }
+
+        obdo_from_inode(oa, inode, valid_flags);
 }
 
-int ll_wr_max_dirty_pages(struct file *file, const char *buffer,
-                          unsigned long count, void *data)
+static void ll_ap_fill_obdo(void *data, int cmd, struct obdo *oa)
 {
-        unsigned long max_dirty;
-        signed long max_dirty_signed;
-        char kernbuf[20], *end;
-        
-        if (count > (sizeof(kernbuf) - 1))
-                return -EINVAL;
+        struct ll_async_page *llap;
+        ENTRY;
 
-        if (copy_from_user(kernbuf, buffer, count))
-                return -EFAULT;
+        llap = LLAP_FROM_COOKIE(data);
+        ll_inode_fill_obdo(llap->llap_page->mapping->host, cmd, oa);
 
-        kernbuf[count] = '\0';
+        EXIT;
+}
 
-        max_dirty_signed = simple_strtol(kernbuf, &end, 0);
-        if (kernbuf == end)
-                return -EINVAL;
-        max_dirty = (unsigned long)max_dirty_signed;
+static void ll_ap_update_obdo(void *data, int cmd, struct obdo *oa,
+                              obd_valid valid)
+{
+        struct ll_async_page *llap;
+        ENTRY;
 
-#if 0
-        if (max_dirty < ll_local_cache_dirty_pages)
-                flush_to_new_max_dirty();
-#endif
+        llap = LLAP_FROM_COOKIE(data);
+        obdo_from_inode(oa, llap->llap_page->mapping->host, valid);
 
-        spin_lock(&ll_local_cache_page_count_lock);
-        CDEBUG(D_CACHE, "changing max_dirty from %lu to %lu\n",
-               ll_max_dirty_pages, max_dirty);
-        ll_max_dirty_pages = max_dirty;
-        spin_unlock(&ll_local_cache_page_count_lock);
-        return count;
+        EXIT;
 }
 
-static int ll_local_cache_full(void)
+static struct obd_capa *ll_ap_lookup_capa(void *data, int cmd)
 {
-        int full = 0;
-        spin_lock(&ll_local_cache_page_count_lock);
-        if (ll_max_dirty_pages &&
-            ll_local_cache_dirty_pages >= ll_max_dirty_pages) {
-                full = 1;
-        }
-        spin_unlock(&ll_local_cache_page_count_lock);
-        /* XXX instrument? */
-        /* XXX trigger async writeback when full, or 75% of full? */
-        return full;
-}
+        struct ll_async_page *llap = LLAP_FROM_COOKIE(data);
+        int opc = cmd & OBD_BRW_WRITE ? CAPA_OPC_OSS_WRITE : CAPA_OPC_OSS_RW;
 
-static void ll_local_cache_flushed_pages(unsigned long pgcount)
-{
-        unsigned long dirty_count;
-        spin_lock(&ll_local_cache_page_count_lock);
-        dirty_count = ll_local_cache_dirty_pages;
-        ll_local_cache_dirty_pages -= pgcount;
-        CDEBUG(D_CACHE, "dirty pages: %lu->%lu)\n",
-               dirty_count, ll_local_cache_dirty_pages);
-        spin_unlock(&ll_local_cache_page_count_lock);
-        LASSERT(dirty_count >= pgcount);
+        return ll_osscapa_get(llap->llap_page->mapping->host, opc);
 }
 
-static void ll_local_cache_dirtied_pages(unsigned long pgcount)
+static struct obd_async_page_ops ll_async_page_ops = {
+        .ap_make_ready =        ll_ap_make_ready,
+        .ap_refresh_count =     ll_ap_refresh_count,
+        .ap_fill_obdo =         ll_ap_fill_obdo,
+        .ap_update_obdo =       ll_ap_update_obdo,
+        .ap_completion =        ll_ap_completion,
+        .ap_lookup_capa =       ll_ap_lookup_capa,
+};
+
+struct ll_async_page *llap_cast_private(struct page *page)
 {
-        unsigned long dirty_count;
-        spin_lock(&ll_local_cache_page_count_lock);
-        dirty_count = ll_local_cache_dirty_pages;
-        ll_local_cache_dirty_pages += pgcount;
-        CDEBUG(D_CACHE, "dirty pages: %lu->%lu\n",
-               dirty_count, ll_local_cache_dirty_pages);
-        spin_unlock(&ll_local_cache_page_count_lock);
-        /* XXX track maximum cached, report to lprocfs */
+        struct ll_async_page *llap = (struct ll_async_page *)page_private(page);
+
+        LASSERTF(llap == NULL || llap->llap_magic == LLAP_MAGIC,
+                 "page %p private %lu gave magic %d which != %d\n",
+                 page, page_private(page), llap->llap_magic, LLAP_MAGIC);
+
+        return llap;
 }
 
-int ll_clear_dirty_pages(struct lustre_handle *conn, struct lov_stripe_md *lsm,
-                         unsigned long start, unsigned long end)
+/* Try to shrink the page cache for the @sbi filesystem by 1/@shrink_fraction.
+ *
+ * There is an llap attached onto every page in lustre, linked off @sbi.
+ * We add an llap to the list so we don't lose our place during list walking.
+ * If llaps in the list are being moved they will only move to the end
+ * of the LRU, and we aren't terribly interested in those pages here (we
+ * start at the beginning of the list where the least-used llaps are.
+ */
+int llap_shrink_cache(struct ll_sb_info *sbi, int shrink_fraction)
 {
-        unsigned long cleared;
-        int rc;
+        struct ll_async_page *llap, dummy_llap = { .llap_magic = 0xd11ad11a };
+        unsigned long total, want, count = 0;
 
-        ENTRY;
-        rc = obd_clear_dirty_pages(conn, lsm, start, end, &cleared);
-        if (!rc)
-                ll_local_cache_flushed_pages(cleared);
-        RETURN(rc);
+        total = sbi->ll_async_page_count;
+
+        /* There can be a large number of llaps (600k or more in a large
+         * memory machine) so the VM 1/6 shrink ratio is likely too much.
+         * Since we are freeing pages also, we don't necessarily want to
+         * shrink so much.  Limit to 40MB of pages + llaps per call. */
+        if (shrink_fraction == 0)
+                want = sbi->ll_async_page_count - sbi->ll_async_page_max + 32;
+        else
+                want = (total + shrink_fraction - 1) / shrink_fraction;
+
+        if (want > 40 << (20 - CFS_PAGE_SHIFT))
+                want = 40 << (20 - CFS_PAGE_SHIFT);
+
+        CDEBUG(D_CACHE, "shrinking %lu of %lu pages (1/%d)\n",
+               want, total, shrink_fraction);
+
+        spin_lock(&sbi->ll_lock);
+        list_add(&dummy_llap.llap_pglist_item, &sbi->ll_pglist);
+
+        while (--total >= 0 && count < want) {
+                struct page *page;
+                int keep;
+
+                if (unlikely(need_resched())) {
+                        spin_unlock(&sbi->ll_lock);
+                        cond_resched();
+                        spin_lock(&sbi->ll_lock);
+                }
+
+                llap = llite_pglist_next_llap(sbi,&dummy_llap.llap_pglist_item);
+                list_del_init(&dummy_llap.llap_pglist_item);
+                if (llap == NULL)
+                        break;
+
+                page = llap->llap_page;
+                LASSERT(page != NULL);
+
+                list_add(&dummy_llap.llap_pglist_item, &llap->llap_pglist_item);
+
+                /* Page needs/undergoing IO */
+                if (TryLockPage(page)) {
+                        LL_CDEBUG_PAGE(D_PAGE, page, "can't lock\n");
+                        continue;
+                }
+
+               keep = (llap->llap_write_queued || PageDirty(page) ||
+                      PageWriteback(page) || (!PageUptodate(page) &&
+                      llap->llap_origin != LLAP_ORIGIN_READAHEAD));
+
+                LL_CDEBUG_PAGE(D_PAGE, page,"%s LRU page: %s%s%s%s%s origin %s\n",
+                               keep ? "keep" : "drop",
+                               llap->llap_write_queued ? "wq " : "",
+                               PageDirty(page) ? "pd " : "",
+                               PageUptodate(page) ? "" : "!pu ",
+                               PageWriteback(page) ? "wb" : "",
+                               llap->llap_defer_uptodate ? "" : "!du",
+                               llap_origins[llap->llap_origin]);
+
+                /* If page is dirty or undergoing IO don't discard it */
+                if (keep) {
+                        unlock_page(page);
+                        continue;
+                }
+
+                page_cache_get(page);
+                spin_unlock(&sbi->ll_lock);
+
+                if (page->mapping != NULL) {
+                        ll_teardown_mmaps(page->mapping,
+                                         (__u64)page->index << CFS_PAGE_SHIFT,
+                                         ((__u64)page->index << CFS_PAGE_SHIFT)|
+                                          ~CFS_PAGE_MASK);
+                        if (!PageDirty(page) && !page_mapped(page)) {
+                                ll_ra_accounting(llap, page->mapping);
+                                ll_truncate_complete_page(page);
+                                ++count;
+                        } else {
+                                LL_CDEBUG_PAGE(D_PAGE, page, "Not dropping page"
+                                                             " because it is "
+                                                             "%s\n",
+                                                              PageDirty(page)?
+                                                              "dirty":"mapped");
+                        }
+                }
+                unlock_page(page);
+                page_cache_release(page);
+
+                spin_lock(&sbi->ll_lock);
+        }
+        list_del(&dummy_llap.llap_pglist_item);
+        spin_unlock(&sbi->ll_lock);
+
+        CDEBUG(D_CACHE, "shrank %lu/%lu and left %lu unscanned\n",
+               count, want, total);
+
+        return count;
 }
 
-int ll_mark_dirty_page(struct lustre_handle *conn, struct lov_stripe_md *lsm,
-                       unsigned long index)
+struct ll_async_page *llap_from_page(struct page *page, unsigned origin)
 {
+        struct ll_async_page *llap;
+        struct obd_export *exp;
+        struct inode *inode = page->mapping->host;
+        struct ll_sb_info *sbi;
         int rc;
-
         ENTRY;
-        if (ll_local_cache_full())
-                RETURN(-EDQUOT);
 
-        rc = obd_mark_page_dirty(conn, lsm, index);
-        if (!rc)
-                ll_local_cache_dirtied_pages(1);
-        RETURN(rc);
+        if (!inode) {
+                static int triggered;
+
+                if (!triggered) {
+                        LL_CDEBUG_PAGE(D_ERROR, page, "Bug 10047. Wrong anon "
+                                       "page received\n");
+                        libcfs_debug_dumpstack(NULL);
+                        triggered = 1;
+                }
+                RETURN(ERR_PTR(-EINVAL));
+        }
+        sbi = ll_i2sbi(inode);
+        LASSERT(ll_async_page_slab);
+        LASSERTF(origin < LLAP__ORIGIN_MAX, "%u\n", origin);
+
+        llap = llap_cast_private(page);
+        if (llap != NULL) {
+                /* move to end of LRU list, except when page is just about to
+                 * die */
+                if (origin != LLAP_ORIGIN_REMOVEPAGE) {
+                        spin_lock(&sbi->ll_lock);
+                        sbi->ll_pglist_gen++;
+                        list_del_init(&llap->llap_pglist_item);
+                        list_add_tail(&llap->llap_pglist_item, &sbi->ll_pglist);
+                        spin_unlock(&sbi->ll_lock);
+                }
+                GOTO(out, llap);
+        }
+
+        exp = ll_i2dtexp(page->mapping->host);
+        if (exp == NULL)
+                RETURN(ERR_PTR(-EINVAL));
+
+        /* limit the number of lustre-cached pages */
+        if (sbi->ll_async_page_count >= sbi->ll_async_page_max)
+                llap_shrink_cache(sbi, 0);
+
+        OBD_SLAB_ALLOC(llap, ll_async_page_slab, CFS_ALLOC_STD,
+                       ll_async_page_slab_size);
+        if (llap == NULL)
+                RETURN(ERR_PTR(-ENOMEM));
+        llap->llap_magic = LLAP_MAGIC;
+        llap->llap_cookie = (void *)llap + size_round(sizeof(*llap));
+
+        rc = obd_prep_async_page(exp, ll_i2info(inode)->lli_smd, NULL, page,
+                                 (obd_off)page->index << CFS_PAGE_SHIFT,
+                                 &ll_async_page_ops, llap, &llap->llap_cookie);
+        if (rc) {
+                OBD_SLAB_FREE(llap, ll_async_page_slab,
+                              ll_async_page_slab_size);
+                RETURN(ERR_PTR(rc));
+        }
+
+        CDEBUG(D_CACHE, "llap %p page %p cookie %p obj off "LPU64"\n", llap,
+               page, llap->llap_cookie, (obd_off)page->index << CFS_PAGE_SHIFT);
+        /* also zeroing the PRIVBITS low order bitflags */
+        __set_page_ll_data(page, llap);
+        llap->llap_page = page;
+        spin_lock(&sbi->ll_lock);
+        sbi->ll_pglist_gen++;
+        sbi->ll_async_page_count++;
+        list_add_tail(&llap->llap_pglist_item, &sbi->ll_pglist);
+        INIT_LIST_HEAD(&llap->llap_pending_write);
+        spin_unlock(&sbi->ll_lock);
+
+ out:
+        if (unlikely(sbi->ll_flags & LL_SBI_CHECKSUM)) {
+                __u32 csum = 0;
+                csum = crc32_le(csum, kmap(page), CFS_PAGE_SIZE);
+                kunmap(page);
+                if (origin == LLAP_ORIGIN_READAHEAD ||
+                    origin == LLAP_ORIGIN_READPAGE) {
+                        llap->llap_checksum = 0;
+                } else if (origin == LLAP_ORIGIN_COMMIT_WRITE ||
+                           llap->llap_checksum == 0) {
+                        llap->llap_checksum = csum;
+                        CDEBUG(D_PAGE, "page %p cksum %x\n", page, csum);
+                } else if (llap->llap_checksum == csum) {
+                        /* origin == LLAP_ORIGIN_WRITEPAGE */
+                        CDEBUG(D_PAGE, "page %p cksum %x confirmed\n",
+                               page, csum);
+                } else {
+                        /* origin == LLAP_ORIGIN_WRITEPAGE */
+                        LL_CDEBUG_PAGE(D_ERROR, page, "old cksum %x != new "
+                                       "%x!\n", llap->llap_checksum, csum);
+                }
+        }
+
+        llap->llap_origin = origin;
+        RETURN(llap);
 }
 
-static int ll_writepage(struct page *page)
+static int queue_or_sync_write(struct obd_export *exp, struct inode *inode,
+                               struct ll_async_page *llap,
+                               unsigned to, obd_flag async_flags)
 {
-        struct inode *inode = page->mapping->host;
-        struct obdo oa;
+        unsigned long size_index = i_size_read(inode) >> CFS_PAGE_SHIFT;
+        struct obd_io_group *oig;
+        struct ll_sb_info *sbi = ll_i2sbi(inode);
+        int rc, noquot = llap->llap_ignore_quota ? OBD_BRW_NOQUOTA : 0;
         ENTRY;
 
-        CDEBUG(D_CACHE, "page %p [lau %d] inode %p\n", page,
-               PageLaunder(page), inode);
-        LASSERT(PageLocked(page));
+        /* _make_ready only sees llap once we've unlocked the page */
+        llap->llap_write_queued = 1;
+        rc = obd_queue_async_io(exp, ll_i2info(inode)->lli_smd, NULL,
+                                llap->llap_cookie, OBD_BRW_WRITE | noquot,
+                                0, 0, 0, async_flags);
+        if (rc == 0) {
+                LL_CDEBUG_PAGE(D_PAGE, llap->llap_page, "write queued\n");
+                GOTO(out, 0);
+        }
+
+        llap->llap_write_queued = 0;
+        /* Do not pass llap here as it is sync write. */
+        llap_write_pending(inode, NULL);
+        
+        rc = oig_init(&oig);
+        if (rc)
+                GOTO(out, rc);
+
+        /* make full-page requests if we are not at EOF (bug 4410) */
+        if (to != CFS_PAGE_SIZE && llap->llap_page->index < size_index) {
+                LL_CDEBUG_PAGE(D_PAGE, llap->llap_page,
+                               "sync write before EOF: size_index %lu, to %d\n",
+                               size_index, to);
+                to = CFS_PAGE_SIZE;
+        } else if (to != CFS_PAGE_SIZE && llap->llap_page->index == size_index) {
+                int size_to = i_size_read(inode) & ~CFS_PAGE_MASK;
+                LL_CDEBUG_PAGE(D_PAGE, llap->llap_page,
+                               "sync write at EOF: size_index %lu, to %d/%d\n",
+                               size_index, to, size_to);
+                if (to < size_to)
+                        to = size_to;
+        }
+
+        /* compare the checksum once before the page leaves llite */
+        if (unlikely((sbi->ll_flags & LL_SBI_CHECKSUM) &&
+                     llap->llap_checksum != 0)) {
+                __u32 csum = 0;
+                struct page *page = llap->llap_page;
+                csum = crc32_le(csum, kmap(page), CFS_PAGE_SIZE);
+                kunmap(page);
+                if (llap->llap_checksum == csum) {
+                        CDEBUG(D_PAGE, "page %p cksum %x confirmed\n",
+                               page, csum);
+                } else {
+                        CERROR("page %p old cksum %x != new cksum %x!\n",
+                               page, llap->llap_checksum, csum);
+                }
+        }
+
+        rc = obd_queue_group_io(exp, ll_i2info(inode)->lli_smd, NULL, oig,
+                                llap->llap_cookie, OBD_BRW_WRITE | noquot,
+                                0, to, 0, ASYNC_READY | ASYNC_URGENT |
+                                ASYNC_COUNT_STABLE | ASYNC_GROUP_SYNC);
+        if (rc)
+                GOTO(free_oig, rc);
+
+        rc = obd_trigger_group_io(exp, ll_i2info(inode)->lli_smd, NULL, oig);
+        if (rc)
+                GOTO(free_oig, rc);
+
+        rc = oig_wait(oig);
+
+        if (!rc && async_flags & ASYNC_READY) {
+                unlock_page(llap->llap_page);
+                if (PageWriteback(llap->llap_page)) {
+                        end_page_writeback(llap->llap_page);
+                }
+        }
+
+        if (rc == 0 && llap_write_complete(inode, llap))
+                ll_queue_done_writing(inode, 0);
 
-        oa.o_id = ll_i2info(inode)->lli_smd->lsm_object_id;
-        oa.o_valid = OBD_MD_FLID;
-        obdo_from_inode(&oa, inode, OBD_MD_FLTYPE | OBD_MD_FLATIME |
-                                    OBD_MD_FLMTIME | OBD_MD_FLCTIME);
+        LL_CDEBUG_PAGE(D_PAGE, llap->llap_page, "sync write returned %d\n", rc);
 
-        RETURN(ll_batch_writepage(inode, &oa, page));
+free_oig:
+        oig_release(oig);
+out:
+        RETURN(rc);
 }
 
-/*
- * we really don't want to start writeback here, we want to give callers some
- * time to further dirty the pages before we write them out.
- */
-static int ll_commit_write(struct file *file, struct page *page,
-                           unsigned from, unsigned to)
+/* update our write count to account for i_size increases that may have
+ * happened since we've queued the page for io. */
+
+/* be careful not to return success without setting the page Uptodate or
+ * the next pass through prepare_write will read in stale data from disk. */
+int ll_commit_write(struct file *file, struct page *page, unsigned from,
+                    unsigned to)
 {
         struct inode *inode = page->mapping->host;
+        struct ll_inode_info *lli = ll_i2info(inode);
+        struct lov_stripe_md *lsm = lli->lli_smd;
+        struct obd_export *exp;
+        struct ll_async_page *llap;
         loff_t size;
         int rc = 0;
         ENTRY;
@@ -607,152 +778,769 @@ static int ll_commit_write(struct file *file, struct page *page,
 
         CDEBUG(D_INODE, "inode %p is writing page %p from %d to %d at %lu\n",
                inode, page, from, to, page->index);
+
+        llap = llap_from_page(page, LLAP_ORIGIN_COMMIT_WRITE);
+        if (IS_ERR(llap))
+                RETURN(PTR_ERR(llap));
+
+        exp = ll_i2dtexp(inode);
+        if (exp == NULL)
+                RETURN(-EINVAL);
+
+        llap->llap_ignore_quota = capable(CAP_SYS_RESOURCE);
+
+        /*
+         * queue a write for some time in the future the first time we
+         * dirty the page.
+         *
+         * This is different from what other file systems do: they usually
+         * just mark page (and some of its buffers) dirty and rely on
+         * balance_dirty_pages() to start a write-back. Lustre wants write-back
+         * to be started earlier for the following reasons:
+         *
+         *     (1) with a large number of clients we need to limit the amount
+         *     of cached data on the clients a lot;
+         *
+         *     (2) large compute jobs generally want compute-only then io-only
+         *     and the IO should complete as quickly as possible;
+         *
+         *     (3) IO is batched up to the RPC size and is async until the
+         *     client max cache is hit
+         *     (/proc/fs/lustre/osc/OSC.../max_dirty_mb)
+         *
+         */
         if (!PageDirty(page)) {
-                lprocfs_counter_incr(ll_i2sbi(inode)->ll_stats,
-                                     LPROC_LL_DIRTY_MISSES);
-                rc = ll_mark_dirty_page(ll_i2obdconn(inode),
-                                        ll_i2info(inode)->lli_smd,
-                                        page->index);
-                if (rc < 0 && rc != -EDQUOT)
-                        RETURN(rc); /* XXX lproc counter here? */
+                ll_stats_ops_tally(ll_i2sbi(inode), LPROC_LL_DIRTY_MISSES, 1);
+
+                rc = queue_or_sync_write(exp, inode, llap, to, 0);
+                if (rc)
+                        GOTO(out, rc);
         } else {
-                lprocfs_counter_incr(ll_i2sbi(inode)->ll_stats,
-                                     LPROC_LL_DIRTY_HITS);
+                ll_stats_ops_tally(ll_i2sbi(inode), LPROC_LL_DIRTY_HITS, 1);
         }
 
-        size = (((obd_off)page->index) << PAGE_SHIFT) + to;
-        if (size > inode->i_size)
-                inode->i_size = size;
+        /* put the page in the page cache, from now on ll_removepage is
+         * responsible for cleaning up the llap.
+         * only set page dirty when it's queued to be write out */
+        if (llap->llap_write_queued)
+                set_page_dirty(page);
+
+out:
+        size = (((obd_off)page->index) << CFS_PAGE_SHIFT) + to;
+        ll_inode_size_lock(inode, 0);
+        if (rc == 0) {
+                lov_stripe_lock(lsm);
+                obd_adjust_kms(exp, lsm, size, 0);
+                lov_stripe_unlock(lsm);
+                if (size > i_size_read(inode))
+                        i_size_write(inode, size);
+                SetPageUptodate(page);
+        } else if (size > i_size_read(inode)) {
+                /* this page beyond the pales of i_size, so it can't be
+                 * truncated in ll_p_r_e during lock revoking. we must
+                 * teardown our book-keeping here. */
+                ll_removepage(page);
+        }
+        ll_inode_size_unlock(inode, 0);
+        RETURN(rc);
+}
 
-        SetPageUptodate(page);
-        set_page_dirty(page);
+static unsigned long ll_ra_count_get(struct ll_sb_info *sbi, unsigned long len)
+{
+        struct ll_ra_info *ra = &sbi->ll_ra_info;
+        unsigned long ret;
+        ENTRY;
 
-        /* This means that we've hit either the local cache limit or the limit
-         * of the OST's grant. */
-        if (rc == -EDQUOT) {
-                struct ll_file_data *fd = file->private_data;
-                struct obdo oa;
-                int rc;
+        spin_lock(&sbi->ll_lock);
+        ret = min(ra->ra_max_pages - ra->ra_cur_pages, len);
+        ra->ra_cur_pages += ret;
+        spin_unlock(&sbi->ll_lock);
 
-                oa.o_id = ll_i2info(inode)->lli_smd->lsm_object_id;
-                memcpy(obdo_handle(&oa), &fd->fd_ost_och.och_fh,
-                       sizeof(fd->fd_ost_och.och_fh));
-                oa.o_valid = OBD_MD_FLID | OBD_MD_FLHANDLE;
-                obdo_from_inode(&oa, inode, OBD_MD_FLTYPE | OBD_MD_FLATIME |
-                                            OBD_MD_FLMTIME | OBD_MD_FLCTIME);
+        RETURN(ret);
+}
 
-                rc = ll_batch_writepage(inode, &oa, page);
-                lock_page(page); /* caller expects to unlock */
-                RETURN(rc);
+static void ll_ra_count_put(struct ll_sb_info *sbi, unsigned long len)
+{
+        struct ll_ra_info *ra = &sbi->ll_ra_info;
+        spin_lock(&sbi->ll_lock);
+        LASSERTF(ra->ra_cur_pages >= len, "r_c_p %lu len %lu\n",
+                 ra->ra_cur_pages, len);
+        ra->ra_cur_pages -= len;
+        spin_unlock(&sbi->ll_lock);
+}
+
+/* called for each page in a completed rpc.*/
+int ll_ap_completion(void *data, int cmd, struct obdo *oa, int rc)
+{
+        struct ll_async_page *llap;
+        struct page *page;
+        int ret = 0;
+        ENTRY;
+
+        llap = LLAP_FROM_COOKIE(data);
+        page = llap->llap_page;
+        LASSERT(PageLocked(page));
+        LASSERT(CheckWriteback(page,cmd));
+        
+        LL_CDEBUG_PAGE(D_PAGE, page, "completing cmd %d with %d\n", cmd, rc);
+
+        if (cmd & OBD_BRW_READ && llap->llap_defer_uptodate)
+                ll_ra_count_put(ll_i2sbi(page->mapping->host), 1);
+
+        if (rc == 0)  {
+                if (cmd & OBD_BRW_READ) {
+                        if (!llap->llap_defer_uptodate)
+                                SetPageUptodate(page);
+                } else {
+                        llap->llap_write_queued = 0;
+                }
+                ClearPageError(page);
+        } else {
+                if (cmd & OBD_BRW_READ) {
+                        llap->llap_defer_uptodate = 0;
+                }
+                SetPageError(page);
+                if (rc == -ENOSPC)
+                        set_bit(AS_ENOSPC, &page->mapping->flags);
+                else
+                        set_bit(AS_EIO, &page->mapping->flags);
         }
 
-        RETURN(0);
-} /* ll_commit_write */
-#else
-static int ll_writepage(struct page *page,
-                        struct writeback_control *wbc)
+        unlock_page(page);
+
+        if (cmd & OBD_BRW_WRITE) {
+                /* Only rc == 0, write succeed, then this page could be deleted
+                 * from the pending_writing list 
+                 */
+                if (rc == 0 && llap_write_complete(page->mapping->host, llap))
+                        ll_queue_done_writing(page->mapping->host, 0);
+        }
+
+        if (PageWriteback(page)) {
+                end_page_writeback(page);
+        }
+        page_cache_release(page);
+
+        RETURN(ret);
+}
+
+/* the kernel calls us here when a page is unhashed from the page cache.
+ * the page will be locked and the kernel is holding a spinlock, so
+ * we need to be careful.  we're just tearing down our book-keeping
+ * here. */
+void ll_removepage(struct page *page)
 {
+        struct inode *inode = page->mapping->host;
+        struct obd_export *exp;
+        struct ll_async_page *llap;
+        struct ll_sb_info *sbi = ll_i2sbi(inode);
+        int rc;
+        ENTRY;
+
+        LASSERT(!in_interrupt());
+
+        /* sync pages or failed read pages can leave pages in the page
+         * cache that don't have our data associated with them anymore */
+        if (page_private(page) == 0) {
+                EXIT;
+                return;
+        }
+
+        LL_CDEBUG_PAGE(D_PAGE, page, "being evicted\n");
+
+        exp = ll_i2dtexp(inode);
+        if (exp == NULL) {
+                CERROR("page %p ind %lu gave null export\n", page, page->index);
+                EXIT;
+                return;
+        }
+
+        llap = llap_from_page(page, LLAP_ORIGIN_REMOVEPAGE);
+        if (IS_ERR(llap)) {
+                CERROR("page %p ind %lu couldn't find llap: %ld\n", page,
+                       page->index, PTR_ERR(llap));
+                EXIT;
+                return;
+        }
 
-        return 0;
+        if (llap_write_complete(inode, llap))
+                ll_queue_done_writing(inode, 0);
+
+        rc = obd_teardown_async_page(exp, ll_i2info(inode)->lli_smd, NULL,
+                                     llap->llap_cookie);
+        if (rc != 0)
+                CERROR("page %p ind %lu failed: %d\n", page, page->index, rc);
+
+        /* this unconditional free is only safe because the page lock
+         * is providing exclusivity to memory pressure/truncate/writeback..*/
+        __clear_page_ll_data(page);
+
+        spin_lock(&sbi->ll_lock);
+        if (!list_empty(&llap->llap_pglist_item))
+                list_del_init(&llap->llap_pglist_item);
+        sbi->ll_pglist_gen++;
+        sbi->ll_async_page_count--;
+        spin_unlock(&sbi->ll_lock);
+        OBD_SLAB_FREE(llap, ll_async_page_slab, ll_async_page_slab_size);
+        EXIT;
 }
-static int ll_commit_write(struct file *file, struct page *page,
-                           unsigned from, unsigned to)
+
+static int ll_page_matches(struct page *page, int fd_flags)
 {
-        return 0;
+        struct lustre_handle match_lockh = {0};
+        struct inode *inode = page->mapping->host;
+        ldlm_policy_data_t page_extent;
+        int flags, matches;
+        ENTRY;
+
+        if (unlikely(fd_flags & LL_FILE_GROUP_LOCKED))
+                RETURN(1);
+
+        page_extent.l_extent.start = (__u64)page->index << CFS_PAGE_SHIFT;
+        page_extent.l_extent.end =
+                page_extent.l_extent.start + CFS_PAGE_SIZE - 1;
+        flags = LDLM_FL_TEST_LOCK | LDLM_FL_BLOCK_GRANTED;
+        if (!(fd_flags & LL_FILE_READAHEAD))
+                flags |= LDLM_FL_CBPENDING;
+        matches = obd_match(ll_i2sbi(inode)->ll_dt_exp,
+                            ll_i2info(inode)->lli_smd, LDLM_EXTENT,
+                            &page_extent, LCK_PR | LCK_PW, &flags, inode,
+                            &match_lockh);
+        RETURN(matches);
 }
-#endif
 
-#if (LINUX_VERSION_CODE < KERNEL_VERSION(2,5,0))
-static int ll_direct_IO(int rw, struct inode *inode, struct kiobuf *iobuf,
-                        unsigned long blocknr, int blocksize)
+static int ll_issue_page_read(struct obd_export *exp,
+                              struct ll_async_page *llap,
+                              struct obd_io_group *oig, int defer)
 {
-        struct ll_inode_info *lli = ll_i2info(inode);
-        struct lov_stripe_md *lsm = lli->lli_smd;
-        struct brw_page *pga;
-        struct ptlrpc_request_set *set;
-        struct obdo oa;
-        int length, i, flags, rc = 0;
-        loff_t offset;
+        struct page *page = llap->llap_page;
+        int rc;
+
+        page_cache_get(page);
+        llap->llap_defer_uptodate = defer;
+        llap->llap_ra_used = 0;
+        rc = obd_queue_group_io(exp, ll_i2info(page->mapping->host)->lli_smd,
+                                NULL, oig, llap->llap_cookie, OBD_BRW_READ, 0,
+                                CFS_PAGE_SIZE, 0, ASYNC_COUNT_STABLE |
+                                                  ASYNC_READY | ASYNC_URGENT);
+        if (rc) {
+                LL_CDEBUG_PAGE(D_ERROR, page, "read queue failed: rc %d\n", rc);
+                page_cache_release(page);
+        }
+        RETURN(rc);
+}
+
+static void ll_ra_stats_inc_unlocked(struct ll_ra_info *ra, enum ra_stat which)
+{
+        LASSERTF(which >= 0 && which < _NR_RA_STAT, "which: %u\n", which);
+        ra->ra_stats[which]++;
+}
+
+static void ll_ra_stats_inc(struct address_space *mapping, enum ra_stat which)
+{
+        struct ll_sb_info *sbi = ll_i2sbi(mapping->host);
+        struct ll_ra_info *ra = &ll_i2sbi(mapping->host)->ll_ra_info;
+
+        spin_lock(&sbi->ll_lock);
+        ll_ra_stats_inc_unlocked(ra, which);
+        spin_unlock(&sbi->ll_lock);
+}
+
+void ll_ra_accounting(struct ll_async_page *llap, struct address_space *mapping)
+{
+        if (!llap->llap_defer_uptodate || llap->llap_ra_used)
+                return;
+
+        ll_ra_stats_inc(mapping, RA_STAT_DISCARDED);
+}
+
+#define RAS_CDEBUG(ras) \
+        CDEBUG(D_READA,                                                      \
+               "lrp %lu cr %lu cp %lu ws %lu wl %lu nra %lu r %lu ri %lu\n", \
+               ras->ras_last_readpage, ras->ras_consecutive_requests,        \
+               ras->ras_consecutive_pages, ras->ras_window_start,            \
+               ras->ras_window_len, ras->ras_next_readahead,                 \
+               ras->ras_requests, ras->ras_request_index);
+
+static int index_in_window(unsigned long index, unsigned long point,
+                           unsigned long before, unsigned long after)
+{
+        unsigned long start = point - before, end = point + after;
+
+        if (start > point)
+               start = 0;
+        if (end < point)
+               end = ~0;
+
+        return start <= index && index <= end;
+}
+
+static struct ll_readahead_state *ll_ras_get(struct file *f)
+{
+        struct ll_file_data       *fd;
+
+        fd = LUSTRE_FPRIVATE(f);
+        return &fd->fd_ras;
+}
+
+void ll_ra_read_in(struct file *f, struct ll_ra_read *rar)
+{
+        struct ll_readahead_state *ras;
+
+        ras = ll_ras_get(f);
+
+        spin_lock(&ras->ras_lock);
+        ras->ras_requests++;
+        ras->ras_request_index = 0;
+        ras->ras_consecutive_requests++;
+        rar->lrr_reader = current;
+
+        list_add(&rar->lrr_linkage, &ras->ras_read_beads);
+        spin_unlock(&ras->ras_lock);
+}
+
+void ll_ra_read_ex(struct file *f, struct ll_ra_read *rar)
+{
+        struct ll_readahead_state *ras;
+
+        ras = ll_ras_get(f);
+
+        spin_lock(&ras->ras_lock);
+        list_del_init(&rar->lrr_linkage);
+        spin_unlock(&ras->ras_lock);
+}
+
+static struct ll_ra_read *ll_ra_read_get_locked(struct ll_readahead_state *ras)
+{
+        struct ll_ra_read *scan;
+
+        list_for_each_entry(scan, &ras->ras_read_beads, lrr_linkage) {
+                if (scan->lrr_reader == current)
+                        return scan;
+        }
+        return NULL;
+}
+
+struct ll_ra_read *ll_ra_read_get(struct file *f)
+{
+        struct ll_readahead_state *ras;
+        struct ll_ra_read         *bead;
+
+        ras = ll_ras_get(f);
+
+        spin_lock(&ras->ras_lock);
+        bead = ll_ra_read_get_locked(ras);
+        spin_unlock(&ras->ras_lock);
+        return bead;
+}
+
+static int ll_readahead(struct ll_readahead_state *ras,
+                         struct obd_export *exp, struct address_space *mapping,
+                         struct obd_io_group *oig, int flags)
+{
+        unsigned long i, start = 0, end = 0, reserved;
+        struct ll_async_page *llap;
+        struct page *page;
+        int rc, ret = 0, match_failed = 0;
+        __u64 kms;
+        unsigned int gfp_mask;
+        struct inode *inode;
+        struct lov_stripe_md *lsm;
+        struct ll_ra_read *bead;
+        struct ost_lvb lvb;
         ENTRY;
 
-        if (!lsm || !lsm->lsm_object_id)
-                RETURN(-EBADF);
+        inode = mapping->host;
+        lsm = ll_i2info(inode)->lli_smd;
+
+        lov_stripe_lock(lsm);
+        inode_init_lvb(inode, &lvb);
+        obd_merge_lvb(ll_i2dtexp(inode), lsm, &lvb, 1);
+        kms = lvb.lvb_size;
+        lov_stripe_unlock(lsm);
+        if (kms == 0) {
+                ll_ra_stats_inc(mapping, RA_STAT_ZERO_LEN);
+                RETURN(0);
+        }
 
-        /* FIXME: io smaller than PAGE_SIZE is broken on ia64 */
-        if ((iobuf->offset & (PAGE_SIZE - 1)) ||
-            (iobuf->length & (PAGE_SIZE - 1)))
-                RETURN(-EINVAL);
+        spin_lock(&ras->ras_lock);
+        bead = ll_ra_read_get_locked(ras);
+        /* Enlarge the RA window to encompass the full read */
+        if (bead != NULL && ras->ras_window_start + ras->ras_window_len <
+            bead->lrr_start + bead->lrr_count) {
+                ras->ras_window_len = bead->lrr_start + bead->lrr_count -
+                                      ras->ras_window_start;
+        }
+        /* Reserve a part of the read-ahead window that we'll be issuing */
+        if (ras->ras_window_len) {
+                start = ras->ras_next_readahead;
+                end = ras->ras_window_start + ras->ras_window_len - 1;
+        }
+        if (end != 0) {
+                /* Truncate RA window to end of file */
+                end = min(end, (unsigned long)((kms - 1) >> CFS_PAGE_SHIFT));
+                ras->ras_next_readahead = max(end, end + 1);
+                RAS_CDEBUG(ras);
+        }
+        spin_unlock(&ras->ras_lock);
 
-        set = ptlrpc_prep_set();
-        if (set == NULL)
-                RETURN(-ENOMEM);
-
-        OBD_ALLOC(pga, sizeof(*pga) * iobuf->nr_pages);
-        if (!pga) {
-                ptlrpc_set_destroy(set);
-                RETURN(-ENOMEM);
-        }
-
-        flags = (rw == WRITE ? OBD_BRW_CREATE : 0) /* | OBD_BRW_DIRECTIO */;
-        offset = ((obd_off)blocknr << inode->i_blkbits);
-        length = iobuf->length;
-
-        for (i = 0, length = iobuf->length; length > 0;
-             length -= pga[i].count, offset += pga[i].count, i++) { /*i last!*/
-                pga[i].pg = iobuf->maplist[i];
-                pga[i].off = offset;
-                /* To the end of the page, or the length, whatever is less */
-                pga[i].count = min_t(int, PAGE_SIZE - (offset & ~PAGE_MASK),
-                                     length);
-                pga[i].flag = flags;
-                if (rw == READ) {
-                        //POISON(kmap(iobuf->maplist[i]), 0xc5, PAGE_SIZE);
-                        //kunmap(iobuf->maplist[i]);
+        if (end == 0) {
+                ll_ra_stats_inc(mapping, RA_STAT_ZERO_WINDOW);
+                RETURN(0);
+        }
+
+        reserved = ll_ra_count_get(ll_i2sbi(inode), end - start + 1);
+        if (reserved < end - start + 1)
+                ll_ra_stats_inc(mapping, RA_STAT_MAX_IN_FLIGHT);
+
+        gfp_mask = GFP_HIGHUSER & ~__GFP_WAIT;
+#ifdef __GFP_NOWARN
+        gfp_mask |= __GFP_NOWARN;
+#endif
+
+        for (i = start; reserved > 0 && !match_failed && i <= end; i++) {
+                /* skip locked pages from previous readpage calls */
+                page = grab_cache_page_nowait_gfp(mapping, i, gfp_mask);
+                if (page == NULL) {
+                        ll_ra_stats_inc(mapping, RA_STAT_FAILED_GRAB_PAGE);
+                        CDEBUG(D_READA, "g_c_p_n failed\n");
+                        continue;
                 }
+
+                /* Check if page was truncated or reclaimed */
+                if (page->mapping != mapping) {
+                        ll_ra_stats_inc(mapping, RA_STAT_WRONG_GRAB_PAGE);
+                        CDEBUG(D_READA, "g_c_p_n returned invalid page\n");
+                        goto next_page;
+                }
+
+                /* we do this first so that we can see the page in the /proc
+                 * accounting */
+                llap = llap_from_page(page, LLAP_ORIGIN_READAHEAD);
+                if (IS_ERR(llap) || llap->llap_defer_uptodate)
+                        goto next_page;
+
+                /* skip completed pages */
+                if (Page_Uptodate(page))
+                        goto next_page;
+
+                /* bail when we hit the end of the lock. */
+                if ((rc = ll_page_matches(page, flags|LL_FILE_READAHEAD)) <= 0){
+                        LL_CDEBUG_PAGE(D_READA | D_PAGE, page,
+                                       "lock match failed: rc %d\n", rc);
+                        ll_ra_stats_inc(mapping, RA_STAT_FAILED_MATCH);
+                        match_failed = 1;
+                        goto next_page;
+                }
+
+                rc = ll_issue_page_read(exp, llap, oig, 1);
+                if (rc == 0) {
+                        reserved--;
+                        ret++;
+                        LL_CDEBUG_PAGE(D_READA| D_PAGE, page,
+                                       "started read-ahead\n");
+                } else {
+        next_page:
+                        LL_CDEBUG_PAGE(D_READA | D_PAGE, page,
+                                       "skipping read-ahead\n");
+
+                        unlock_page(page);
+                }
+                page_cache_release(page);
         }
 
-        oa.o_id = lsm->lsm_object_id;
-        oa.o_valid = OBD_MD_FLID;
-        obdo_from_inode(&oa, inode, OBD_MD_FLTYPE | OBD_MD_FLATIME |
-                                    OBD_MD_FLMTIME | OBD_MD_FLCTIME);
+        LASSERTF(reserved >= 0, "reserved %lu\n", reserved);
+        if (reserved != 0)
+                ll_ra_count_put(ll_i2sbi(inode), reserved);
+        if (i == end + 1 && end == (kms >> CFS_PAGE_SHIFT))
+                ll_ra_stats_inc(mapping, RA_STAT_EOF);
+
+        /* if we didn't get to the end of the region we reserved from
+         * the ras we need to go back and update the ras so that the
+         * next read-ahead tries from where we left off.  we only do so
+         * if the region we failed to issue read-ahead on is still ahead
+         * of the app and behind the next index to start read-ahead from */
+        if (i != end + 1) {
+                spin_lock(&ras->ras_lock);
+                if (i < ras->ras_next_readahead &&
+                    index_in_window(i, ras->ras_window_start, 0,
+                                    ras->ras_window_len)) {
+                        ras->ras_next_readahead = i;
+                        RAS_CDEBUG(ras);
+                }
+                spin_unlock(&ras->ras_lock);
+        }
 
-        if (rw == WRITE)
-                lprocfs_counter_add(ll_i2sbi(inode)->ll_stats,
-                                    LPROC_LL_DIRECT_WRITE, iobuf->length);
-        else
-                lprocfs_counter_add(ll_i2sbi(inode)->ll_stats,
-                                    LPROC_LL_DIRECT_READ, iobuf->length);
-        rc = obd_brw_async(rw == WRITE ? OBD_BRW_WRITE : OBD_BRW_READ,
-                           ll_i2obdconn(inode), &oa, lsm, iobuf->nr_pages, pga,
-                           set, NULL);
-        if (rc) {
-                CDEBUG(rc == -ENOSPC ? D_INODE : D_ERROR,
-                       "error from obd_brw_async: rc = %d\n", rc);
-        } else {
-                rc = ptlrpc_set_wait(set);
-                if (rc)
-                        CERROR("error from callback: rc = %d\n", rc);
+        RETURN(ret);
+}
+
+static void ras_set_start(struct ll_readahead_state *ras, unsigned long index)
+{
+        ras->ras_window_start = index & (~((1024 * 1024 >> CFS_PAGE_SHIFT) - 1));
+}
+
+/* called with the ras_lock held or from places where it doesn't matter */
+static void ras_reset(struct ll_readahead_state *ras, unsigned long index)
+{
+        ras->ras_last_readpage = index;
+        ras->ras_consecutive_requests = 0;
+        ras->ras_consecutive_pages = 0;
+        ras->ras_window_len = 0;
+        ras_set_start(ras, index);
+        ras->ras_next_readahead = max(ras->ras_window_start, index);
+
+        RAS_CDEBUG(ras);
+}
+
+void ll_readahead_init(struct inode *inode, struct ll_readahead_state *ras)
+{
+        spin_lock_init(&ras->ras_lock);
+        ras_reset(ras, 0);
+        ras->ras_requests = 0;
+        INIT_LIST_HEAD(&ras->ras_read_beads);
+}
+
+static void ras_update(struct ll_sb_info *sbi, struct inode *inode,
+                       struct ll_readahead_state *ras, unsigned long index,
+                       unsigned hit)
+{
+        struct ll_ra_info *ra = &sbi->ll_ra_info;
+        int zero = 0;
+        ENTRY;
+
+        spin_lock(&sbi->ll_lock);
+        spin_lock(&ras->ras_lock);
+
+        ll_ra_stats_inc_unlocked(ra, hit ? RA_STAT_HIT : RA_STAT_MISS);
+
+        /* reset the read-ahead window in two cases.  First when the app seeks
+         * or reads to some other part of the file.  Secondly if we get a
+         * read-ahead miss that we think we've previously issued.  This can
+         * be a symptom of there being so many read-ahead pages that the VM is
+         * reclaiming it before we get to it. */
+        if (!index_in_window(index, ras->ras_last_readpage, 8, 8)) {
+                zero = 1;
+                ll_ra_stats_inc_unlocked(ra, RA_STAT_DISTANT_READPAGE);
+        } else if (!hit && ras->ras_window_len &&
+                   index < ras->ras_next_readahead &&
+                   index_in_window(index, ras->ras_window_start, 0,
+                                   ras->ras_window_len)) {
+                zero = 1;
+                ll_ra_stats_inc_unlocked(ra, RA_STAT_MISS_IN_WINDOW);
+        }
+
+        /* On the second access to a file smaller than the tunable
+         * ra_max_read_ahead_whole_pages trigger RA on all pages in the
+         * file up to ra_max_pages.  This is simply a best effort and
+         * only occurs once per open file.  Normal RA behavior is reverted
+         * to for subsequent IO.  The mmap case does not increment
+         * ras_requests and thus can never trigger this behavior. */
+        if (ras->ras_requests == 2 && !ras->ras_request_index) {
+                __u64 kms_pages;
+
+                kms_pages = (i_size_read(inode) + CFS_PAGE_SIZE - 1) >>
+                            CFS_PAGE_SHIFT;
+
+                CDEBUG(D_READA, "kmsp "LPU64" mwp %lu mp %lu\n", kms_pages,
+                       ra->ra_max_read_ahead_whole_pages, ra->ra_max_pages);
+
+                if (kms_pages &&
+                    kms_pages <= ra->ra_max_read_ahead_whole_pages) {
+                        ras->ras_window_start = 0;
+                        ras->ras_last_readpage = 0;
+                        ras->ras_next_readahead = 0;
+                        ras->ras_window_len = min(ra->ra_max_pages,
+                                ra->ra_max_read_ahead_whole_pages);
+                        GOTO(out_unlock, 0);
+                }
+        }
+
+        if (zero) {
+                ras_reset(ras, index);
+                GOTO(out_unlock, 0);
         }
-        ptlrpc_set_destroy(set);
-        if (rc == 0)
-                rc = iobuf->length;
 
-        OBD_FREE(pga, sizeof(*pga) * iobuf->nr_pages);
+        ras->ras_last_readpage = index;
+        ras->ras_consecutive_pages++;
+        ras_set_start(ras, index);
+        ras->ras_next_readahead = max(ras->ras_window_start,
+                                      ras->ras_next_readahead);
+
+        /* Trigger RA in the mmap case where ras_consecutive_requests
+         * is not incremented and thus can't be used to trigger RA */
+        if (!ras->ras_window_len && ras->ras_consecutive_pages == 3) {
+                ras->ras_window_len = 1024 * 1024 >> CFS_PAGE_SHIFT;
+                GOTO(out_unlock, 0);
+        }
+
+        /* The initial ras_window_len is set to the request size.  To avoid
+         * uselessly reading and discarding pages for random IO the window is
+         * only increased once per consecutive request received. */
+        if (ras->ras_consecutive_requests > 1 && !ras->ras_request_index) {
+                ras->ras_window_len = min(ras->ras_window_len +
+                                          (1024 * 1024 >> CFS_PAGE_SHIFT),
+                                          ra->ra_max_pages);
+        }
+
+        EXIT;
+out_unlock:
+        RAS_CDEBUG(ras);
+        ras->ras_request_index++;
+        spin_unlock(&ras->ras_lock);
+        spin_unlock(&sbi->ll_lock);
+        return;
+}
+
+int ll_writepage(struct page *page)
+{
+        struct inode *inode = page->mapping->host;
+        struct ll_inode_info *lli = ll_i2info(inode);
+        struct obd_export *exp;
+        struct ll_async_page *llap;
+        int rc = 0;
+        ENTRY;
+
+        LASSERT(!PageDirty(page));
+        LASSERT(PageLocked(page));
+
+        exp = ll_i2dtexp(inode);
+        if (exp == NULL)
+                GOTO(out, rc = -EINVAL);
+
+        llap = llap_from_page(page, LLAP_ORIGIN_WRITEPAGE);
+        if (IS_ERR(llap))
+                GOTO(out, rc = PTR_ERR(llap));
+
+        LASSERT(!PageWriteback(page));
+        set_page_writeback(page);
+
+        page_cache_get(page);
+        if (llap->llap_write_queued) {
+                LL_CDEBUG_PAGE(D_PAGE, page, "marking urgent\n");
+                rc = obd_set_async_flags(exp, lli->lli_smd, NULL,
+                                         llap->llap_cookie,
+                                         ASYNC_READY | ASYNC_URGENT);
+        } else {
+                rc = queue_or_sync_write(exp, inode, llap, CFS_PAGE_SIZE,
+                                         ASYNC_READY | ASYNC_URGENT);
+        }
+        if (rc)
+                page_cache_release(page);
+out:
+        if (rc) {
+                if (!lli->lli_async_rc)
+                        lli->lli_async_rc = rc;
+                /* re-dirty page on error so it retries write */
+                if (PageWriteback(page)) {
+                        end_page_writeback(page);
+                }
+                /* resend page only for not started IO*/
+                if (!PageError(page))
+                        ll_redirty_page(page);
+                unlock_page(page);
+        }
         RETURN(rc);
 }
-#endif
 
-//#endif
+/*
+ * for now we do our readpage the same on both 2.4 and 2.5.  The kernel's
+ * read-ahead assumes it is valid to issue readpage all the way up to
+ * i_size, but our dlm locks make that not the case.  We disable the
+ * kernel's read-ahead and do our own by walking ahead in the page cache
+ * checking for dlm lock coverage.  the main difference between 2.4 and
+ * 2.6 is how read-ahead gets batched and issued, but we're using our own,
+ * so they look the same.
+ */
+int ll_readpage(struct file *filp, struct page *page)
+{
+        struct ll_file_data *fd = LUSTRE_FPRIVATE(filp);
+        struct inode *inode = page->mapping->host;
+        struct obd_export *exp;
+        struct ll_async_page *llap;
+        struct obd_io_group *oig = NULL;
+        int rc;
+        ENTRY;
+
+        LASSERT(PageLocked(page));
+        LASSERT(!PageUptodate(page));
+        CDEBUG(D_VFSTRACE, "VFS Op:inode=%lu/%u(%p),offset=%Lu=%#Lx\n",
+               inode->i_ino, inode->i_generation, inode,
+               (((loff_t)page->index) << CFS_PAGE_SHIFT),
+               (((loff_t)page->index) << CFS_PAGE_SHIFT));
+        LASSERT(atomic_read(&filp->f_dentry->d_inode->i_count) > 0);
+
+        if (!ll_i2info(inode)->lli_smd) {
+                /* File with no objects - one big hole */
+                /* We use this just for remove_from_page_cache that is not
+                 * exported, we'd make page back up to date. */
+                ll_truncate_complete_page(page);
+                clear_page(kmap(page));
+                kunmap(page);
+                SetPageUptodate(page);
+                unlock_page(page);
+                RETURN(0);
+        }
 
-struct address_space_operations ll_aops = {
-        readpage: ll_readpage,
-#if (LINUX_VERSION_CODE <= KERNEL_VERSION(2,5,0))
-        direct_IO: ll_direct_IO,
-#endif
-        writepage: ll_writepage,
-        sync_page: block_sync_page,
-        prepare_write: ll_prepare_write,
-        commit_write: ll_commit_write,
-        bmap: NULL
-//#endif
-};
+        rc = oig_init(&oig);
+        if (rc < 0)
+                GOTO(out, rc);
+
+        exp = ll_i2dtexp(inode);
+        if (exp == NULL)
+                GOTO(out, rc = -EINVAL);
+
+        llap = llap_from_page(page, LLAP_ORIGIN_READPAGE);
+        if (IS_ERR(llap))
+                GOTO(out, rc = PTR_ERR(llap));
+
+        if (ll_i2sbi(inode)->ll_ra_info.ra_max_pages)
+                ras_update(ll_i2sbi(inode), inode, &fd->fd_ras, page->index,
+                           llap->llap_defer_uptodate);
+
+        if (llap->llap_defer_uptodate) {
+                llap->llap_ra_used = 1;
+                rc = ll_readahead(&fd->fd_ras, exp, page->mapping, oig,
+                                  fd->fd_flags);
+                if (rc > 0)
+                        obd_trigger_group_io(exp, ll_i2info(inode)->lli_smd,
+                                             NULL, oig);
+                LL_CDEBUG_PAGE(D_PAGE, page, "marking uptodate from defer\n");
+                SetPageUptodate(page);
+                unlock_page(page);
+                GOTO(out_oig, rc = 0);
+        }
+
+        if (likely((fd->fd_flags & LL_FILE_IGNORE_LOCK) == 0)) {
+                rc = ll_page_matches(page, fd->fd_flags);
+                if (rc < 0) {
+                        LL_CDEBUG_PAGE(D_ERROR, page, "lock match failed: rc %d\n", rc);
+                        GOTO(out, rc);
+                }
+
+                if (rc == 0) {
+                        CWARN("ino %lu page %lu (%llu) not covered by "
+                              "a lock (mmap?).  check debug logs.\n",
+                              inode->i_ino, page->index,
+                              (long long)page->index << CFS_PAGE_SHIFT);
+                }
+        }
+
+        rc = ll_issue_page_read(exp, llap, oig, 0);
+        if (rc)
+                GOTO(out, rc);
+
+        LL_CDEBUG_PAGE(D_PAGE, page, "queued readpage\n");
+        if (ll_i2sbi(inode)->ll_ra_info.ra_max_pages)
+                ll_readahead(&fd->fd_ras, exp, page->mapping, oig,
+                             fd->fd_flags);
+
+        rc = obd_trigger_group_io(exp, ll_i2info(inode)->lli_smd, NULL, oig);
+
+out:
+        if (rc)
+                unlock_page(page);
+out_oig:
+        if (oig != NULL)
+                oig_release(oig);
+        RETURN(rc);
+}