reiserfs: Protect dquot_writeback_dquots() by s_umount semaphore

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dquot_writeback_dquots() expects s_umount semaphore to be held to
protect it from other concurrent quota operations. reiserfs_sync_fs()
can call dquot_writeback_dquots() without holding s_umount semaphore
when called from flush_old_commits().

Fix the problem by grabbing s_umount in flush_old_commits(). However we
have to be careful and use only trylock since reiserfs_cancel_old_sync()
can be waiting for flush_old_commits() to complete while holding
s_umount semaphore. Possible postponing of sync work is not a big deal
though as that is only an opportunistic flush.

Fixes: 9d1ccbe70e
Reported-by: Jan Beulich <jbeulich@suse.com>
Signed-off-by: Jan Kara <jack@suse.cz>

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Jan Kara 2017-04-05 14:17:30 +02:00

parent 71b0576bdb

commit 1e0e653f11

1 changed files with 14 additions and 0 deletions

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fs/reiserfs/super.c

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