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| author | Christian Brauner <christian.brauner@ubuntu.com> | 2021-01-21 16:19:51 +0300 |
|---|---|---|
| committer | Christian Brauner <christian.brauner@ubuntu.com> | 2021-01-24 16:29:34 +0300 |
| commit | fbdc2f6c40f6528fa0db79c73e844451234f3e26 (patch) | |
| tree | a3b3519ed8fb7bf257e2e1a7abd74483189e5471 | |
| parent | e58ace1a0fa9d578f85f556b4b88c5fe9b871d08 (diff) | |
| download | linux-fbdc2f6c40f6528fa0db79c73e844451234f3e26.tar.xz | |
fs: split out functions to hold writers
When a mount is marked read-only we set MNT_WRITE_HOLD on it if there
aren't currently any active writers. Split this logic out into simple
helpers that we can use in follow-up patches.
Link: https://lore.kernel.org/r/20210121131959.646623-33-christian.brauner@ubuntu.com
Cc: David Howells <dhowells@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel@vger.kernel.org
Suggested-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
| -rw-r--r-- | fs/namespace.c | 24 |
1 files changed, 18 insertions, 6 deletions
diff --git a/fs/namespace.c b/fs/namespace.c index 367f1c7cb6db..774ae5f74716 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -470,10 +470,8 @@ void mnt_drop_write_file(struct file *file) } EXPORT_SYMBOL(mnt_drop_write_file); -static int mnt_make_readonly(struct mount *mnt) +static inline int mnt_hold_writers(struct mount *mnt) { - int ret = 0; - mnt->mnt.mnt_flags |= MNT_WRITE_HOLD; /* * After storing MNT_WRITE_HOLD, we'll read the counters. This store @@ -498,15 +496,29 @@ static int mnt_make_readonly(struct mount *mnt) * we're counting up here. */ if (mnt_get_writers(mnt) > 0) - ret = -EBUSY; - else - mnt->mnt.mnt_flags |= MNT_READONLY; + return -EBUSY; + + return 0; +} + +static inline void mnt_unhold_writers(struct mount *mnt) +{ /* * MNT_READONLY must become visible before ~MNT_WRITE_HOLD, so writers * that become unheld will see MNT_READONLY. */ smp_wmb(); mnt->mnt.mnt_flags &= ~MNT_WRITE_HOLD; +} + +static int mnt_make_readonly(struct mount *mnt) +{ + int ret; + + ret = mnt_hold_writers(mnt); + if (!ret) + mnt->mnt.mnt_flags |= MNT_READONLY; + mnt_unhold_writers(mnt); return ret; } |