From 880b9577855edddda1e732748e849c63199d489b Mon Sep 17 00:00:00 2001 From: "Darrick J. Wong" Date: Mon, 17 Jul 2023 09:00:09 -0700 Subject: 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 Reviewed-by: Christoph Hellwig Reviewed-by: Dave Chinner Reviewed-by: Jan Kara --- fs/f2fs/gc.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) (limited to 'fs/f2fs') diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c index 01effd3fcb6c..a1ca394bc327 100644 --- a/fs/f2fs/gc.c +++ b/fs/f2fs/gc.c @@ -2181,12 +2181,14 @@ out_drop_write: if (err) return err; - err = freeze_super(sbi->sb); + err = freeze_super(sbi->sb, FREEZE_HOLDER_USERSPACE); if (err) return err; if (f2fs_readonly(sbi->sb)) { - thaw_super(sbi->sb); + err = thaw_super(sbi->sb, FREEZE_HOLDER_USERSPACE); + if (err) + return err; return -EROFS; } @@ -2240,6 +2242,6 @@ recover_out: out_err: f2fs_up_write(&sbi->cp_global_sem); f2fs_up_write(&sbi->gc_lock); - thaw_super(sbi->sb); + thaw_super(sbi->sb, FREEZE_HOLDER_USERSPACE); return err; } -- cgit