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| author | Darrick J. Wong <djwong@kernel.org> | 2023-07-17 09:00:09 -0700 |
|---|---|---|
| committer | Darrick J. Wong <djwong@kernel.org> | 2023-07-17 09:00:09 -0700 |
| commit | 880b9577855edddda1e732748e849c63199d489b (patch) | |
| tree | 8864baba5793708725a2c440be96c218846eeaef /Documentation/filesystems | |
| parent | fdf0eaf11452d72945af31804e2a1048ee1b574c (diff) | |
| download | linux-880b9577855edddda1e732748e849c63199d489b.tar.gz | |
fs: distinguish between user initiated freeze and kernel initiated freeze
Userspace can freeze a filesystem using the FIFREEZE ioctl or by
suspending the block device; this state persists until userspace thaws
the filesystem with the FITHAW ioctl or resuming the block device.
Since commit 18e9e5104fcd ("Introduce freeze_super and thaw_super for
the fsfreeze ioctl") we only allow the first freeze command to succeed.
The kernel may decide that it is necessary to freeze a filesystem for
its own internal purposes, such as suspends in progress, filesystem fsck
activities, or quiescing a device prior to removal. Userspace thaw
commands must never break a kernel freeze, and kernel thaw commands
shouldn't undo userspace's freeze command.
Introduce a couple of freeze holder flags and wire it into the
sb_writers state. One kernel and one userspace freeze are allowed to
coexist at the same time; the filesystem will not thaw until both are
lifted.
I wonder if the f2fs/gfs2 code should be using a kernel freeze here, but
for now we'll use FREEZE_HOLDER_USERSPACE to preserve existing
behaviors.
Cc: mcgrof@kernel.org
Cc: jack@suse.cz
Cc: hch@infradead.org
Cc: ruansy.fnst@fujitsu.com
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Diffstat (limited to 'Documentation/filesystems')
| -rw-r--r-- | Documentation/filesystems/vfs.rst | 6 |
1 files changed, 4 insertions, 2 deletions
diff --git a/Documentation/filesystems/vfs.rst b/Documentation/filesystems/vfs.rst index cb2a97e4987265..176dd4606d100f 100644 --- a/Documentation/filesystems/vfs.rst +++ b/Documentation/filesystems/vfs.rst @@ -260,9 +260,11 @@ filesystem. The following members are defined: void (*evict_inode) (struct inode *); void (*put_super) (struct super_block *); int (*sync_fs)(struct super_block *sb, int wait); - int (*freeze_super) (struct super_block *); + int (*freeze_super) (struct super_block *sb, + enum freeze_holder who); int (*freeze_fs) (struct super_block *); - int (*thaw_super) (struct super_block *); + int (*thaw_super) (struct super_block *sb, + enum freeze_wholder who); int (*unfreeze_fs) (struct super_block *); int (*statfs) (struct dentry *, struct kstatfs *); int (*remount_fs) (struct super_block *, int *, char *); |