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authorJosef Bacik <josef@redhat.com>2010-03-23 17:34:56 +0300
committerAl Viro <viro@zeniv.linux.org.uk>2010-05-22 02:31:18 +0400
commit18e9e5104fcd9a973ffe3eed3816c87f2a1b6cd2 (patch)
tree635369c866fcb384223618c878e0b4c317790634 /fs/block_dev.c
parente1e46bf1866317d4f86f66bf18d3f07317d9f9ee (diff)
downloadlinux-18e9e5104fcd9a973ffe3eed3816c87f2a1b6cd2.tar.xz
Introduce freeze_super and thaw_super for the fsfreeze ioctl
Currently the way we do freezing is by passing sb>s_bdev to freeze_bdev and then letting it do all the work. But freezing is more of an fs thing, and doesn't really have much to do with the bdev at all, all the work gets done with the super. In btrfs we do not populate s_bdev, since we can have multiple bdev's for one fs and setting s_bdev makes removing devices from a pool kind of tricky. This means that freezing a btrfs filesystem fails, which causes us to corrupt with things like tux-on-ice which use the fsfreeze mechanism. So instead of populating sb->s_bdev with a random bdev in our pool, I've broken the actual fs freezing stuff into freeze_super and thaw_super. These just take the super_block that we're freezing and does the appropriate work. It's basically just copy and pasted from freeze_bdev. I've then converted freeze_bdev over to use the new super helpers. I've tested this with ext4 and btrfs and verified everything continues to work the same as before. The only new gotcha is multiple calls to the fsfreeze ioctl will return EBUSY if the fs is already frozen. I thought this was a better solution than adding a freeze counter to the super_block, but if everybody hates this idea I'm open to suggestions. Thanks, Signed-off-by: Josef Bacik <josef@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'fs/block_dev.c')
-rw-r--r--fs/block_dev.c74
1 files changed, 16 insertions, 58 deletions
diff --git a/fs/block_dev.c b/fs/block_dev.c
index 39cb6591d37d..1aba036dcabf 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -245,38 +245,14 @@ struct super_block *freeze_bdev(struct block_device *bdev)
sb = get_active_super(bdev);
if (!sb)
goto out;
- down_write(&sb->s_umount);
- if (sb->s_flags & MS_RDONLY) {
- sb->s_frozen = SB_FREEZE_TRANS;
- up_write(&sb->s_umount);
+ error = freeze_super(sb);
+ if (error) {
+ deactivate_super(sb);
+ bdev->bd_fsfreeze_count--;
mutex_unlock(&bdev->bd_fsfreeze_mutex);
- return sb;
- }
-
- sb->s_frozen = SB_FREEZE_WRITE;
- smp_wmb();
-
- sync_filesystem(sb);
-
- sb->s_frozen = SB_FREEZE_TRANS;
- smp_wmb();
-
- sync_blockdev(sb->s_bdev);
-
- if (sb->s_op->freeze_fs) {
- error = sb->s_op->freeze_fs(sb);
- if (error) {
- printk(KERN_ERR
- "VFS:Filesystem freeze failed\n");
- sb->s_frozen = SB_UNFROZEN;
- deactivate_locked_super(sb);
- bdev->bd_fsfreeze_count--;
- mutex_unlock(&bdev->bd_fsfreeze_mutex);
- return ERR_PTR(error);
- }
+ return ERR_PTR(error);
}
- up_write(&sb->s_umount);
-
+ deactivate_super(sb);
out:
sync_blockdev(bdev);
mutex_unlock(&bdev->bd_fsfreeze_mutex);
@@ -297,40 +273,22 @@ int thaw_bdev(struct block_device *bdev, struct super_block *sb)
mutex_lock(&bdev->bd_fsfreeze_mutex);
if (!bdev->bd_fsfreeze_count)
- goto out_unlock;
+ goto out;
error = 0;
if (--bdev->bd_fsfreeze_count > 0)
- goto out_unlock;
+ goto out;
if (!sb)
- goto out_unlock;
-
- BUG_ON(sb->s_bdev != bdev);
- down_write(&sb->s_umount);
- if (sb->s_flags & MS_RDONLY)
- goto out_unfrozen;
-
- if (sb->s_op->unfreeze_fs) {
- error = sb->s_op->unfreeze_fs(sb);
- if (error) {
- printk(KERN_ERR
- "VFS:Filesystem thaw failed\n");
- sb->s_frozen = SB_FREEZE_TRANS;
- bdev->bd_fsfreeze_count++;
- mutex_unlock(&bdev->bd_fsfreeze_mutex);
- return error;
- }
- }
-
-out_unfrozen:
- sb->s_frozen = SB_UNFROZEN;
- smp_wmb();
- wake_up(&sb->s_wait_unfrozen);
+ goto out;
- if (sb)
- deactivate_locked_super(sb);
-out_unlock:
+ error = thaw_super(sb);
+ if (error) {
+ bdev->bd_fsfreeze_count++;
+ mutex_unlock(&bdev->bd_fsfreeze_mutex);
+ return error;
+ }
+out:
mutex_unlock(&bdev->bd_fsfreeze_mutex);
return 0;
}