Re: [PATCH 2/3] fs: make thaw_super_locked() really just a helper
From: Jan Kara <jack@suse.cz>
Date: 2018-05-03 15:07:49
Also in:
linux-fsdevel, linux-pm, lkml
On Fri 20-04-18 16:59:03, Luis R. Rodriguez wrote:
thaw_super_locked() was added via commit 08fdc8a0138a ("buffer.c: call
thaw_super during emergency thaw") merged on v4.17 to help with the
ability so that the caller can take charge of handling the s_umount lock,
however, it has left all* of the failure handling including unlocking
lock of s_umount inside thaw_super_locked().
This does not make thaw_super_locked() flexible. For instance we may
later want to use it with the abilty to handle unfolding of the locks
ourselves.
Change thaw_super_locked() to really just be a helper, and let the
callers deal with all the error handling.And do you have use for the new thaw_super_locked()? Because the new semantics with having to deal with deactivate_locked_super() does not seem ideal either so as a standalone cleanup patch it does not look too useful.
This commit introeuces no functional changes.
^^^ introduces Honza
quoted hunk ↗ jump to hunk
--- fs/super.c | 27 ++++++++++++++++++++------- 1 file changed, 20 insertions(+), 7 deletions(-)diff --git a/fs/super.c b/fs/super.c index 9d0eb5e20a1f..82bc74a16f06 100644 --- a/fs/super.c +++ b/fs/super.c@@ -937,10 +937,15 @@ void emergency_remount(void) static void do_thaw_all_callback(struct super_block *sb) { + int error; + down_write(&sb->s_umount); if (sb->s_root && sb->s_flags & MS_BORN) { emergency_thaw_bdev(sb); - thaw_super_locked(sb); + error = thaw_super_locked(sb); + if (error) + up_write(&sb->s_umount); + deactivate_locked_super(sb); } else { up_write(&sb->s_umount); }@@ -1532,14 +1537,13 @@ int freeze_super(struct super_block *sb) } EXPORT_SYMBOL(freeze_super); +/* Caller takes the sb->s_umount rw_semaphore lock and handles active count */ static int thaw_super_locked(struct super_block *sb) { int error; - if (sb->s_writers.frozen != SB_FREEZE_COMPLETE) { - up_write(&sb->s_umount); + if (sb->s_writers.frozen != SB_FREEZE_COMPLETE) return -EINVAL; - } if (sb_rdonly(sb)) { sb->s_writers.frozen = SB_UNFROZEN;@@ -1554,7 +1558,6 @@ static int thaw_super_locked(struct super_block *sb) printk(KERN_ERR "VFS:Filesystem thaw failed\n"); lockdep_sb_freeze_release(sb); - up_write(&sb->s_umount); return error; } }@@ -1563,7 +1566,6 @@ static int thaw_super_locked(struct super_block *sb) sb_freeze_unlock(sb); out: wake_up(&sb->s_writers.wait_unfrozen); - deactivate_locked_super(sb); return 0; }@@ -1575,7 +1577,18 @@ static int thaw_super_locked(struct super_block *sb) */ int thaw_super(struct super_block *sb) { + int error; + down_write(&sb->s_umount); - return thaw_super_locked(sb); + error = thaw_super_locked(sb); + if (error) { + up_write(&sb->s_umount); + goto out; + } + + deactivate_locked_super(sb); + +out: + return error; } EXPORT_SYMBOL(thaw_super);-- 2.16.3
-- Jan Kara [off-list ref] SUSE Labs, CR