WSL2-Linux-Kernel/fs/ext4
Takashi Sato c4be0c1dc4 filesystem freeze: add error handling of write_super_lockfs/unlockfs
Currently, ext3 in mainline Linux doesn't have the freeze feature which
suspends write requests.  So, we cannot take a backup which keeps the
filesystem's consistency with the storage device's features (snapshot and
replication) while it is mounted.

In many case, a commercial filesystem (e.g.  VxFS) has the freeze feature
and it would be used to get the consistent backup.

If Linux's standard filesystem ext3 has the freeze feature, we can do it
without a commercial filesystem.

So I have implemented the ioctls of the freeze feature.
I think we can take the consistent backup with the following steps.
1. Freeze the filesystem with the freeze ioctl.
2. Separate the replication volume or create the snapshot
   with the storage device's feature.
3. Unfreeze the filesystem with the unfreeze ioctl.
4. Take the backup from the separated replication volume
   or the snapshot.

This patch:

VFS:
Changed the type of write_super_lockfs and unlockfs from "void"
to "int" so that they can return an error.
Rename write_super_lockfs and unlockfs of the super block operation
freeze_fs and unfreeze_fs to avoid a confusion.

ext3, ext4, xfs, gfs2, jfs:
Changed the type of write_super_lockfs and unlockfs from "void"
to "int" so that write_super_lockfs returns an error if needed,
and unlockfs always returns 0.

reiserfs:
Changed the type of write_super_lockfs and unlockfs from "void"
to "int" so that they always return 0 (success) to keep a current behavior.

Signed-off-by: Takashi Sato <t-sato@yk.jp.nec.com>
Signed-off-by: Masayuki Hamaguchi <m-hamaguchi@ys.jp.nec.com>
Cc: <xfs-masters@oss.sgi.com>
Cc: <linux-ext4@vger.kernel.org>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Dave Kleikamp <shaggy@austin.ibm.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Alasdair G Kergon <agk@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-01-09 16:54:42 -08:00
..
Kconfig fs/Kconfig: move ext2, ext3, ext4, JBD, JBD2 out 2008-10-20 11:43:59 -07:00
Makefile ext4: Rename ext4dev to ext4 2008-10-10 20:02:48 -04:00
acl.c [PATCH] sanitize ->permission() prototype 2008-07-26 20:53:14 -04:00
acl.h ext4: Rename ext4dev to ext4 2008-10-10 20:02:48 -04:00
balloc.c ext4: Use new buffer_head flag to check uninit group bitmaps initialization 2009-01-05 21:49:55 -05:00
bitmap.c ext4: Change unsigned long to unsigned int 2008-11-05 00:14:04 -05:00
dir.c ext4: Make printk's consistently prefixed with "EXT4-fs: " 2009-01-06 00:20:32 -05:00
ext4.h Merge branch 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4 2009-01-08 17:14:59 -08:00
ext4_extents.h ext4: Remove i_ext_generation from ext4_inode_info structure 2008-11-04 18:46:03 -05:00
ext4_i.h ext4: Make ext4_group_t be an unsigned int 2009-01-05 22:18:16 -05:00
ext4_jbd2.c ext4: Allow ext4 to run without a journal 2009-01-07 00:06:22 -05:00
ext4_jbd2.h ext4: Remove "extents" mount option 2009-01-06 14:53:16 -05:00
ext4_sb.h fs: introduce bgl_lock_ptr() 2009-01-04 13:33:20 -08:00
extents.c Merge branch 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4 2009-01-08 17:14:59 -08:00
file.c ext4: sparse fixes 2008-11-22 15:04:59 -05:00
fsync.c ext4: Add debugging markers that can be used by systemtap 2008-10-05 20:50:06 -04:00
group.h ext4: Rename read_block_bitmap() to ext4_read_block_bitmap() 2008-07-11 19:27:31 -04:00
hash.c ext4: Add support for non-native signed/unsigned htree hash algorithms 2008-10-28 13:21:44 -04:00
ialloc.c ext4: Remove "extents" mount option 2009-01-06 14:53:16 -05:00
inode.c Merge branch 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4 2009-01-08 17:14:59 -08:00
ioctl.c ext4: Allow ext4 to run without a journal 2009-01-07 00:06:22 -05:00
mballoc.c ext4: Fix s_dirty_blocks_counter if block allocation failed with nodelalloc 2009-01-05 21:49:12 -05:00
mballoc.h ext4: Don't allow new groups to be added during block allocation 2009-01-05 21:46:55 -05:00
migrate.c ext4: Remove "extents" mount option 2009-01-06 14:53:16 -05:00
namei.c Merge branch 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4 2009-01-08 17:14:59 -08:00
namei.h [PATCH] ext4: rename ext4 symbols to avoid duplication of ext3 symbols 2006-10-11 11:14:15 -07:00
resize.c ext4: mark the blocks/inode bitmap beyond end of group as used 2009-01-05 21:46:04 -05:00
super.c filesystem freeze: add error handling of write_super_lockfs/unlockfs 2009-01-09 16:54:42 -08:00
symlink.c ext4: Rename ext4dev to ext4 2008-10-10 20:02:48 -04:00
xattr.c ext4: Allow ext4 to run without a journal 2009-01-07 00:06:22 -05:00
xattr.h ext4: Rename ext4dev to ext4 2008-10-10 20:02:48 -04:00
xattr_security.c ext4: move headers out of include/linux 2008-04-29 18:13:32 -04:00
xattr_trusted.c ext4: remove double definitions of xattr macros 2008-07-11 19:27:31 -04:00
xattr_user.c ext4: remove double definitions of xattr macros 2008-07-11 19:27:31 -04:00