quota: Hold s_umount in exclusive mode when enabling / disabling quotas

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Currently we hold s_umount semaphore only in shared mode when enabling
or disabling quotas and use dqonoff_mutex for serializing quota state
changes on a filesystem and also quota state changes with other places
depending on current quota state. Using dedicated mutex for this causes
possible deadlocks during filesystem freezing (see following commit for
details) so we transition to using s_umount semaphore for the necessary
synchronization whose lock ordering is properly handled by the
filesystem freezing code. As a start grab s_umount in exclusive mode
when enabling / disabling quotas.

Signed-off-by: Jan Kara <jack@suse.cz>

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This commit is contained in:

Jan Kara 2016-11-23 13:16:10 +01:00

parent ba6379f7e6

commit 7d6cd73d33

2 changed files with 24 additions and 3 deletions

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11

fs/quota/dquot.c

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16

fs/quota/quota.c

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