From: Christian Brauner <christian.brau...@ubuntu.com> 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.brau...@ubuntu.com Cc: David Howells <dhowe...@redhat.com> Cc: Al Viro <v...@zeniv.linux.org.uk> Cc: linux-fsde...@vger.kernel.org Suggested-by: Christoph Hellwig <h...@lst.de> Reviewed-by: Christoph Hellwig <h...@lst.de> Signed-off-by: Christian Brauner <christian.brau...@ubuntu.com> (cherry picked from commit fbdc2f6c40f6528fa0db79c73e844451234f3e26) https://jira.sw.ru/browse/PSBM-144416 Signed-off-by: Pavel Tikhomirov <ptikhomi...@virtuozzo.com> --- fs/namespace.c | 24 ++++++++++++++++++------ 1 file changed, 18 insertions(+), 6 deletions(-) diff --git a/fs/namespace.c b/fs/namespace.c index c03e21575d08..a40a217f9871 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -570,10 +570,8 @@ 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 @@ -598,15 +596,29 @@ 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; } -- 2.39.2 _______________________________________________ Devel mailing list Devel@openvz.org https://lists.openvz.org/mailman/listinfo/devel
