1 files changed, 41 insertions, 21 deletions

diff --git a/fs/bfs/file.c b/fs/bfs/file.c
index 911b4ccf470f..b11e63e8fbcd 100644
--- a/fs/bfs/file.c
+++ b/fs/bfs/file.c
@@ -2,6 +2,11 @@
  *      fs/bfs/file.c
  *      BFS file operations.
  *      Copyright (C) 1999,2000 Tigran Aivazian <tigran@veritas.com>
+ *
+ *      Make the file block allocation algorithm understand the size
+ *      of the underlying block device.
+ *      Copyright (C) 2007 Dmitri Vorobiev <dmitri.vorobiev@gmail.com>
+ *
  */
 
 #include <linux/fs.h>
@@ -27,7 +32,8 @@ const struct file_operations bfs_file_operations = {
         .splice_read    = generic_file_splice_read,
 };
 
-static int bfs_move_block(unsigned long from, unsigned long to, struct super_block *sb)
+static int bfs_move_block(unsigned long from, unsigned long to,
+                                        struct super_block *sb)
 {
         struct buffer_head *bh, *new;
 
@@ -43,21 +49,22 @@ static int bfs_move_block(unsigned long from, unsigned long to, struct super_blo
 }
 
 static int bfs_move_blocks(struct super_block *sb, unsigned long start,
-                           unsigned long end, unsigned long where)
+                                unsigned long end, unsigned long where)
 {
         unsigned long i;
 
         dprintf("%08lx-%08lx->%08lx\n", start, end, where);
         for (i = start; i <= end; i++)
                 if(bfs_move_block(i, where + i, sb)) {
-                        dprintf("failed to move block %08lx -> %08lx\n", i, where + i);
+                        dprintf("failed to move block %08lx -> %08lx\n", i,
+                                                                where + i);
                         return -EIO;
                 }
         return 0;
 }
 
-static int bfs_get_block(struct inode * inode, sector_t block, 
-        struct buffer_head * bh_result, int create)
+static int bfs_get_block(struct inode *inode, sector_t block,
+                        struct buffer_head *bh_result, int create)
 {
         unsigned long phys;
         int err;
@@ -66,9 +73,6 @@ static int bfs_get_block(struct inode * inode, sector_t block,
         struct bfs_inode_info *bi = BFS_I(inode);
         struct buffer_head *sbh = info->si_sbh;
 
-        if (block > info->si_blocks)
-                return -EIO;
-
         phys = bi->i_sblock + block;
         if (!create) {
                 if (phys <= bi->i_eblock) {
@@ -79,21 +83,29 @@ static int bfs_get_block(struct inode * inode, sector_t block,
                 return 0;
         }
 
-        /* if the file is not empty and the requested block is within the range
-           of blocks allocated for this file, we can grant it */
-        if (inode->i_size && phys <= bi->i_eblock) {
+        /*
+         * If the file is not empty and the requested block is within the
+         * range of blocks allocated for this file, we can grant it.
+         */
+        if (bi->i_sblock && (phys <= bi->i_eblock)) {
                 dprintf("c=%d, b=%08lx, phys=%08lx (interim block granted)\n", 
                                 create, (unsigned long)block, phys);
                 map_bh(bh_result, sb, phys);
                 return 0;
         }
 
-        /* the rest has to be protected against itself */
+        /* The file will be extended, so let's see if there is enough space. */
+        if (phys >= info->si_blocks)
+                return -ENOSPC;
+
+        /* The rest has to be protected against itself. */
         lock_kernel();
 
-        /* if the last data block for this file is the last allocated
-           block, we can extend the file trivially, without moving it
-           anywhere */
+        /*
+         * If the last data block for this file is the last allocated
+         * block, we can extend the file trivially, without moving it
+         * anywhere.
+         */
         if (bi->i_eblock == info->si_lf_eblk) {
                 dprintf("c=%d, b=%08lx, phys=%08lx (simple extension)\n", 
                                 create, (unsigned long)block, phys);
@@ -106,13 +118,19 @@ static int bfs_get_block(struct inode * inode, sector_t block,
                 goto out;
         }
 
-        /* Ok, we have to move this entire file to the next free block */
+        /* Ok, we have to move this entire file to the next free block. */
         phys = info->si_lf_eblk + 1;
-        if (bi->i_sblock) { /* if data starts on block 0 then there is no data */
+        if (phys + block >= info->si_blocks) {
+                err = -ENOSPC;
+                goto out;
+        }
+
+        if (bi->i_sblock) {
                 err = bfs_move_blocks(inode->i_sb, bi->i_sblock, 
-                                bi->i_eblock, phys);
+                                                bi->i_eblock, phys);
                 if (err) {
-                        dprintf("failed to move ino=%08lx -> fs corruption\n", inode->i_ino);
+                        dprintf("failed to move ino=%08lx -> fs corruption\n",
+                                                                inode->i_ino);
                         goto out;
                 }
         } else
@@ -124,8 +142,10 @@ static int bfs_get_block(struct inode * inode, sector_t block,
         phys += block;
         info->si_lf_eblk = bi->i_eblock = phys;
 
-        /* this assumes nothing can write the inode back while we are here
-         * and thus update inode->i_blocks! (XXX)*/
+        /*
+         * This assumes nothing can write the inode back while we are here
+         * and thus update inode->i_blocks! (XXX)
+         */
         info->si_freeb -= bi->i_eblock - bi->i_sblock + 1 - inode->i_blocks;
         mark_inode_dirty(inode);
         mark_buffer_dirty(sbh);