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authorDarrick J. Wong <djwong@kernel.org>2023-07-17 09:00:09 -0700
committerDarrick J. Wong <djwong@kernel.org>2023-07-17 09:00:09 -0700
commit880b9577855edddda1e732748e849c63199d489b (patch)
tree8864baba5793708725a2c440be96c218846eeaef /fs/ioctl.c
parentfdf0eaf11452d72945af31804e2a1048ee1b574c (diff)
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 'fs/ioctl.c')
-rw-r--r--fs/ioctl.c8
1 files changed, 4 insertions, 4 deletions
diff --git a/fs/ioctl.c b/fs/ioctl.c
index 5b2481cd4750..a56cbceedcd1 100644
--- a/fs/ioctl.c
+++ b/fs/ioctl.c
@@ -396,8 +396,8 @@ static int ioctl_fsfreeze(struct file *filp)
/* Freeze */
if (sb->s_op->freeze_super)
- return sb->s_op->freeze_super(sb);
- return freeze_super(sb);
+ return sb->s_op->freeze_super(sb, FREEZE_HOLDER_USERSPACE);
+ return freeze_super(sb, FREEZE_HOLDER_USERSPACE);
}
static int ioctl_fsthaw(struct file *filp)
@@ -409,8 +409,8 @@ static int ioctl_fsthaw(struct file *filp)
/* Thaw */
if (sb->s_op->thaw_super)
- return sb->s_op->thaw_super(sb);
- return thaw_super(sb);
+ return sb->s_op->thaw_super(sb, FREEZE_HOLDER_USERSPACE);
+ return thaw_super(sb, FREEZE_HOLDER_USERSPACE);
}
static int ioctl_file_dedupe_range(struct file *file,