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Btrfs: deal with errors in write_dev_supers 

If you try to mount -o loop a restored file system it will panic if the file
ends up being smaller than the original disk.  This is because we go to try and
get a block for a super that may be past the EOF which makes __getblk return
NULL for a buffer head when we aren't expecting it to.  Fix this by dealing with
this case and just jacking up the errors count.  With this patch we no longer
panic when mounting a restored file system loopback.  Thanks,

Signed-off-by: Josef Bacik <jbacik@fusionio.com>
This commit is contained in:
Josef Bacik 2013-04-29 10:05:57 -04:00
parent 3650860b90
commit 634554dc0a
1 changed files with 11 additions and 1 deletions
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12
fs/btrfs/disk-io.c
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@ -2986,7 +2986,10 @@ static int write_dev_supers(struct btrfs_device *device,
if (wait) {
bh = __find_get_block(device->bdev, bytenr / 4096,
BTRFS_SUPER_INFO_SIZE);
BUG_ON(!bh);
if (!bh) {
errors++;
continue;
}
wait_on_buffer(bh);
if (!buffer_uptodate(bh))
errors++;
@ -3013,6 +3016,13 @@ static int write_dev_supers(struct btrfs_device *device,
*/
bh = __getblk(device->bdev, bytenr / 4096,
BTRFS_SUPER_INFO_SIZE);
if (!bh) {
printk(KERN_ERR "btrfs: couldn't get super "
"buffer head for bytenr %Lu\n", bytenr);
errors++;
continue;
}
memcpy(bh->b_data, sb, BTRFS_SUPER_INFO_SIZE);
/* one reference for submit_bh */