lustre/obdfs/rw.c

   1 /*
   2  * OBDFS Super operations
   3  *
   4  * Copryright (C) 1999 Stelias Computing Inc,
   5  *                (author Peter J. Braam <braam@stelias.com>)
   6  * Copryright (C) 1999 Seagate Technology Inc.
   7  */
   8
   9
  10 #include <linux/config.h>
  11 #include <linux/kernel.h>
  12 #include <linux/mm.h>
  13 #include <linux/string.h>
  14 #include <linux/stat.h>
  15 #include <linux/errno.h>
  16 #include <linux/locks.h>
  17 #include <linux/unistd.h>
  18
  19 #include <asm/system.h>
  20 #include <asm/uaccess.h>
  21
  22 #include <linux/fs.h>
  23 #include <linux/stat.h>
  24 #include <asm/uaccess.h>
  25 #include <linux/vmalloc.h>
  26 #include <asm/segment.h>
  27 #include <linux/mm.h>
  28 #include <linux/pagemap.h>
  29 #include <linux/smp_lock.h>
  30
  31 #include <../obd/linux/obd_support.h>
  32 #include <../obd/linux/obd_sim.h>
  33 #include <obdfs.h>
  34
  35 /* VFS super_block ops */
  36
  37 /* returns the page unlocked, but with a reference */
  38 int obdfs_readpage(struct file *file, struct page *page)
  39 {
  40         struct obdfs_sb_info *sbi;
  41         struct super_block *sb = file->f_dentry->d_inode->i_sb;
  42         int rc;
  43
  44         ENTRY;
  45
  46         /* XXX flush stuff */
  47         sbi = sb->u.generic_sbp;
  48         PDEBUG(page, READ);
  49         rc =  sbi->osi_ops->o_brw(READ, sbi->osi_conn_info.conn_id,
  50                       file->f_dentry->d_inode->i_ino, page);
  51         if (rc == PAGE_SIZE ) {
  52                 SetPageUptodate(page);
  53                 UnlockPage(page);
  54         }
  55         PDEBUG(page, READ);
  56         if ( rc == PAGE_SIZE )
  57                 rc = 0;
  58         return rc;
  59
  60 }
  61
  62 /*
  63  * This does the "real" work of the write. The generic routine has
  64  * allocated the page, locked it, done all the page alignment stuff
  65  * calculations etc. Now we should just copy the data from user
  66  * space and write it back to the real medium..
  67  *
  68  * If the writer ends up delaying the write, the writer needs to
  69  * increment the page use counts until he is done with the page.
  70  */
  71 int obdfs_write_one_page(struct file *file, struct page *page, unsigned long offset, unsigned long bytes, const char * buf)
  72 {
  73         long status;
  74
  75         bytes -= copy_from_user((u8*)page_address(page) + offset, buf, bytes);
  76         status = -EFAULT;
  77         CDEBUG(D_INODE, "page offset %ld, bytes %ld, offset %ld, page addr %lx, writing: %s, beg of page %s\n", page->offset, bytes, offset, page_address(page), ((char *) page_address(page)) + offset, (char *)page_address(page));
  78         if (bytes) {
  79                 lock_kernel();
  80                 status = obdfs_writepage(file, page);
  81                 unlock_kernel();
  82         }
  83         if ( status != PAGE_SIZE )
  84                 return status;
  85         else
  86                 return bytes;
  87 }
  88
  89
  90
  91
  92 /* returns the page unlocked, but with a reference */
  93 int obdfs_writepage(struct file *file, struct page *page)
  94 {
  95         struct obdfs_sb_info *sbi;
  96         struct super_block *sb = file->f_dentry->d_inode->i_sb;
  97         int rc;
  98
  99         ENTRY;
 100         PDEBUG(page,WRITE);
 101         /* XXX flush stuff */
 102         sbi = sb->u.generic_sbp;
 103
 104         rc = sbi->osi_ops->o_brw(WRITE, sbi->osi_conn_info.conn_id,
 105                       file->f_dentry->d_inode->i_ino, page);
 106         SetPageUptodate(page);
 107         PDEBUG(page,WRITE);
 108         return rc;
 109 }
 110
 111
 112 /*
 113    page is returned unlocked, with the up to date flag set,
 114    and held, i.e. caller must do a page_put
 115 */
 116 struct page *obdfs_getpage(struct inode *inode, unsigned long offset)
 117 {
 118         unsigned long new_page;
 119         struct page ** hash;
 120         struct page * page;
 121         struct obdfs_sb_info *sbi;
 122         struct super_block *sb = inode->i_sb;
 123
 124         ENTRY;
 125
 126         sbi = sb->u.generic_sbp;
 127
 128         page = find_get_page(inode, offset);
 129         if (page && Page_Uptodate(page)) {
 130                 PDEBUG(page,READ);
 131                 return page;
 132         }
 133
 134         if (page && !Page_Uptodate(page) ) {
 135                 CDEBUG(D_INODE, "Page found but not up to date\n");
 136         }
 137
 138         /* page_cache_alloc returns address of page */
 139         new_page = page_cache_alloc();
 140         if (!new_page)
 141                 return NULL;
 142
 143         /* corresponding struct page in the mmap */
 144         hash = page_hash(inode, offset);
 145         page = page_cache_entry(new_page);
 146         if (!add_to_page_cache_unique(page, inode, offset, hash)) {
 147                 CDEBUG(D_INODE, "Page not found. Reading it.\n");
 148                 PDEBUG(page,READ);
 149                 sbi->osi_ops->o_brw(READ, sbi->osi_conn_info.conn_id,
 150                                     inode->i_ino, page);
 151                 UnlockPage(page);
 152                 SetPageUptodate(page);
 153                 return page;
 154         }
 155         /*
 156          * We arrive here in the unlikely event that someone
 157          * raced with us and added our page to the cache first.
 158          */
 159         CDEBUG(D_INODE, "Page not found. Someone raced us.\n");
 160         PDEBUG(page,READ);
 161         return page;
 162 }
 163
 164
 165
 166 struct file_operations obdfs_file_operations = {
 167         NULL,                   /* lseek - default */
 168         generic_file_read,      /* read */
 169         obdfs_file_write,     /* write - bad */
 170         obdfs_readdir,          /* readdir */
 171         NULL,                   /* poll - default */
 172         NULL,                   /* ioctl */
 173         NULL,                   /* mmap */
 174         NULL,                   /* no special open code */
 175         NULL,                   /* flush */
 176         NULL,                   /* no special release code */
 177         NULL,                   /* fsync */
 178         NULL,                   /* fasync */
 179         NULL,                   /* check_media_change */
 180         NULL                    /* revalidate */
 181 };
 182
 183 struct inode_operations obdfs_inode_ops = {
 184         &obdfs_file_operations, /* default directory file-ops */
 185         NULL,           /* create */
 186         obdfs_lookup,   /* lookup */
 187         NULL,           /* link */
 188         NULL,           /* unlink */
 189         NULL,           /* symlink */
 190         NULL,           /* mkdir */
 191         NULL,           /* rmdir */
 192         NULL,           /* mknod */
 193         NULL,           /* rename */
 194         NULL,           /* readlink */
 195         NULL,           /* follow_link */
 196         NULL,           /* get_block */
 197         obdfs_readpage, /* readpage */
 198         obdfs_writepage, /* writepage */
 199         NULL,           /* flushpage */
 200         NULL,           /* truncate */
 201         NULL,           /* permission */
 202         NULL,           /* smap */
 203         NULL            /* revalidate */
 204 };