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, 0);
  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         struct obdfs_sb_info *sbi = file->f_dentry->d_inode->i_sb->u.generic_sbp;
  75
  76         ENTRY;
  77         if ( !Page_Uptodate(page) ) {
  78                 status =  sbi->osi_ops->o_brw(READ,
  79                                               sbi->osi_conn_info.conn_id,
  80                                               file->f_dentry->d_inode->i_ino,
  81                                               page, 1);
  82                 if (status == PAGE_SIZE ) {
  83                         SetPageUptodate(page);
  84                 } else {
  85                         return status;
  86                 }
  87         }
  88         bytes -= copy_from_user((u8*)page_address(page) + offset, buf, bytes);
  89         status = -EFAULT;
  90
  91         if (bytes) {
  92                 lock_kernel();
  93                 status = obdfs_writepage(file, page);
  94                 unlock_kernel();
  95         }
  96         EXIT;
  97         if ( status != PAGE_SIZE )
  98                 return status;
  99         else
 100                 return bytes;
 101 }
 102
 103
 104
 105
 106 /* returns the page unlocked, but with a reference */
 107 int obdfs_writepage(struct file *file, struct page *page)
 108 {
 109         struct obdfs_sb_info *sbi = file->f_dentry->d_inode->i_sb->u.generic_sbp;
 110         int rc;
 111
 112         ENTRY;
 113         PDEBUG(page, "WRITEPAGE");
 114         /* XXX flush stuff */
 115
 116         rc = sbi->osi_ops->o_brw(WRITE, sbi->osi_conn_info.conn_id,
 117                       file->f_dentry->d_inode->i_ino, page, 1);
 118         SetPageUptodate(page);
 119         PDEBUG(page,"WRITEPAGE");
 120         return rc;
 121 }
 122
 123
 124 /*
 125    page is returned unlocked, with the up to date flag set,
 126    and held, i.e. caller must do a page_put
 127 */
 128 struct page *obdfs_getpage(struct inode *inode, unsigned long offset, int create, int locked)
 129 {
 130         unsigned long new_page;
 131         struct page ** hash;
 132         struct page * page;
 133         struct obdfs_sb_info *sbi;
 134         struct super_block *sb = inode->i_sb;
 135
 136         ENTRY;
 137
 138         sbi = sb->u.generic_sbp;
 139
 140         page = find_lock_page(inode, offset);
 141         if (page && Page_Uptodate(page)) {
 142                 PDEBUG(page,"GETPAGE");
 143                 if (!locked)
 144                         UnlockPage(page);
 145                 EXIT;
 146                 return page;
 147         }
 148
 149         if (page && !Page_Uptodate(page) ) {
 150                 CDEBUG(D_INODE, "Page found but not up to date\n");
 151         }
 152
 153         /* page_cache_alloc returns the VM address of page */
 154         new_page = page_cache_alloc();
 155         if (!new_page)
 156                 return NULL;
 157
 158         /* corresponding struct page in the mmap */
 159         hash = page_hash(inode, offset);
 160         page = page_cache_entry(new_page);
 161         if (!add_to_page_cache_unique(page, inode, offset, hash)) {
 162                 CDEBUG(D_INODE, "Page not found. Reading it.\n");
 163                 PDEBUG(page,"GETPAGE - before reading");
 164                 sbi->osi_ops->o_brw(READ, sbi->osi_conn_info.conn_id,
 165                                     inode->i_ino, page, create);
 166                 if ( !locked )
 167                         UnlockPage(page);
 168                 SetPageUptodate(page);
 169                 PDEBUG(page,"GETPAGE - after reading");
 170                 EXIT;
 171                 return page;
 172         }
 173         /*
 174          * We arrive here in the unlikely event that someone
 175          * raced with us and added our page to the cache first.
 176          */
 177         CDEBUG(D_INODE, "Page not found. Someone raced us.\n");
 178         PDEBUG(page,"GETPAGE");
 179         EXIT;
 180         return page;
 181 }
 182
 183
 184
 185 struct file_operations obdfs_file_ops = {
 186         NULL,                   /* lseek - default */
 187         generic_file_read,      /* read */
 188         obdfs_file_write,     /* write - bad */
 189         obdfs_readdir,          /* readdir */
 190         NULL,                   /* poll - default */
 191         NULL,                   /* ioctl */
 192         NULL,                   /* mmap */
 193         NULL,                   /* no special open code */
 194         NULL,                   /* flush */
 195         NULL,                   /* no special release code */
 196         NULL,                   /* fsync */
 197         NULL,                   /* fasync */
 198         NULL,                   /* check_media_change */
 199         NULL                    /* revalidate */
 200 };
 201
 202 struct inode_operations obdfs_inode_ops = {
 203         &obdfs_file_ops,        /* default directory file-ops */
 204         obdfs_create,   /* create */
 205         obdfs_lookup,   /* lookup */
 206         obdfs_link,     /* link */
 207         obdfs_unlink,   /* unlink */
 208         obdfs_symlink,  /* symlink */
 209         obdfs_mkdir,    /* mkdir */
 210         obdfs_rmdir,    /* rmdir */
 211         obdfs_mknod,    /* mknod */
 212         obdfs_rename,   /* rename */
 213         NULL,           /* readlink */
 214         NULL,           /* follow_link */
 215         NULL,           /* get_block */
 216         obdfs_readpage, /* readpage */
 217         obdfs_writepage, /* writepage */
 218         NULL,           /* flushpage */
 219         NULL,           /* truncate */
 220         NULL,           /* permission */
 221         NULL,           /* smap */
 222         NULL            /* revalidate */
 223 };