LU-5700 llite: handle concurrent use of cob_transient_pages

With the lockless __generic_file_aio_write introduced in LU-1669,
ll_direct_IO_26 is no longer protected by the inode i_isem.

This renders obsoltete checks that all transient pages have been
handled before and after entry, and requires atomic access to their
counter.

Signed-off-by: Stephen Champion <schamp@sgi.com>
Change-Id: Ie1545b2123a5ca7d9a8cac130ff387fc06955629
Reviewed-on: http://review.whamcloud.com/12179
Tested-by: Jenkins
Reviewed-by: Jinshan Xiong <jinshan.xiong@intel.com>
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Bobi Jam <bobijam@gmail.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>

diff --git a/lustre/include/lclient.h b/lustre/include/lclient.h
index cb02a9a..c6ea235 100644 (file)
--- a/lustre/include/lclient.h
+++ b/lustre/include/lclient.h
@@ -207,12 +207,12 @@ struct ccc_object {
          */
        struct list_head        cob_pending_list;
 
-        /**
-         * Access this counter is protected by inode->i_sem. Now that
-         * the lifetime of transient pages must be covered by inode sem,
-         * we don't need to hold any lock..
-         */
-        int                     cob_transient_pages;
+       /**
+        * Number of transient pages.  This is no longer protected by i_sem,
+        * and needs to be atomic.  This is not actually used for anything,
+        * and can probably be removed.
+        */
+       atomic_t                cob_transient_pages;
        /**
         * Number of outstanding mmaps on this file.
         *

diff --git a/lustre/llite/lcommon_cl.c b/lustre/llite/lcommon_cl.c
index 510ab9d..338727f 100644 (file)
--- a/lustre/llite/lcommon_cl.c
+++ b/lustre/llite/lcommon_cl.c
@@ -347,13 +347,13 @@ struct lu_object *ccc_object_alloc(const struct lu_env *env,
 }
 
 int ccc_object_init0(const struct lu_env *env,
-                            struct ccc_object *vob,
-                            const struct cl_object_conf *conf)
+                    struct ccc_object *vob,
+                    const struct cl_object_conf *conf)
 {
-        vob->cob_inode = conf->coc_inode;
-        vob->cob_transient_pages = 0;
+       vob->cob_inode = conf->coc_inode;
+       atomic_set(&vob->cob_transient_pages, 0);
        cl_object_page_init(&vob->cob_cl, sizeof(struct ccc_page));
-        return 0;
+       return 0;
 }
 
 int ccc_object_init(const struct lu_env *env, struct lu_object *obj,

diff --git a/lustre/llite/rw26.c b/lustre/llite/rw26.c
index 046c099..73774ae 100644 (file)
--- a/lustre/llite/rw26.c
+++ b/lustre/llite/rw26.c
@@ -377,7 +377,6 @@ static ssize_t ll_direct_IO_26(int rw, struct kiocb *iocb,
         struct cl_io *io;
         struct file *file = iocb->ki_filp;
         struct inode *inode = file->f_mapping->host;
-        struct ccc_object *obj = cl_inode2ccc(inode);
         long count = iov_length(iov, nr_segs);
         long tot_bytes = 0, result = 0;
         struct ll_inode_info *lli = ll_i2info(inode);
@@ -411,7 +410,6 @@ static ssize_t ll_direct_IO_26(int rw, struct kiocb *iocb,
         io = ccc_env_io(env)->cui_cl.cis_io;
         LASSERT(io != NULL);
 
-        LASSERT(obj->cob_transient_pages == 0);
         for (seg = 0; seg < nr_segs; seg++) {
                 long iov_left = iov[seg].iov_len;
                 unsigned long user_addr = (unsigned long)iov[seg].iov_base;
@@ -471,8 +469,6 @@ static ssize_t ll_direct_IO_26(int rw, struct kiocb *iocb,
                 }
         }
 out:
-       LASSERT(obj->cob_transient_pages == 0);
-
         if (tot_bytes > 0) {
                struct ccc_io *cio = ccc_env_io(env);
 

diff --git a/lustre/llite/vvp_object.c b/lustre/llite/vvp_object.c
index 53c5f12..434e141 100644 (file)
--- a/lustre/llite/vvp_object.c
+++ b/lustre/llite/vvp_object.c
@@ -61,7 +61,8 @@ static int vvp_object_print(const struct lu_env *env, void *cookie,
 
        (*p)(env, cookie, "(%s %d %d) inode: %p ",
             list_empty(&obj->cob_pending_list) ? "-" : "+",
-            obj->cob_transient_pages, atomic_read(&obj->cob_mmap_cnt),
+            atomic_read(&obj->cob_transient_pages),
+            atomic_read(&obj->cob_mmap_cnt),
             inode);
        if (inode) {
                lli = ll_i2info(inode);

diff --git a/lustre/llite/vvp_page.c b/lustre/llite/vvp_page.c
index cf32538..2b384d8 100644 (file)
--- a/lustre/llite/vvp_page.c
+++ b/lustre/llite/vvp_page.c
@@ -495,7 +495,7 @@ static void vvp_transient_page_fini(const struct lu_env *env,
        struct ccc_object *clobj = cl2ccc(clp->cp_obj);
 
        vvp_page_fini_common(cp);
-       clobj->cob_transient_pages--;
+       atomic_dec(&clobj->cob_transient_pages);
 }
 
 static const struct cl_page_operations vvp_transient_page_ops = {
@@ -544,7 +544,7 @@ int vvp_page_init(const struct lu_env *env, struct cl_object *obj,
 
                cl_page_slice_add(page, &cpg->cpg_cl, obj, index,
                                &vvp_transient_page_ops);
-               clobj->cob_transient_pages++;
+               atomic_inc(&clobj->cob_transient_pages);
        }
        return 0;
 }