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The following test script triggers a deadlock on ext2 filesystem: while true; do quotaon /dev/hda >&/dev/null; usleep $RANDOM; done & while true; do quotaoff /dev/hda >&/dev/null; usleep $RANDOM; done & I found there is a potential deadlock between quotaon and quotaoff (or quotasync). Basically, all of quotactl operations need to be protected by dqonoff_mutex. vfs_quota_off and vfs_quota_sync also call sb->s_op->quota_write that needs to grab the i_mutex of the quota file. But in vfs_quota_on_inode (called from quotaon operation), the current code tries to grab the i_mutex of the quota file first before getting quonoff_mutex. Reverse the order in which we take locks in vfs_quota_on_inode(). Jan Kara: Changed changelog to be more readable, made lockdep happy with I_MUTEX_QUOTA. Signed-off-by: Jiaying Zhang <jiayingz@google.com> Signed-off-by: Jan Kara <jack@suse.cz> |
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| .. | ||
| dquot.c | ||
| Kconfig | ||
| Makefile | ||
| quota_tree.c | ||
| quota_tree.h | ||
| quota_v1.c | ||
| quota_v2.c | ||
| quota.c | ||
| quotaio_v1.h | ||
| quotaio_v2.h | ||