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9d1ccbe70e
Writeback quota is protected by s_umount semaphore held for reading because every writeback must be protected by that lock (grabbed either by the generic writeback code or by quotactl handler). Getting next available ID in quota file, querying quota state, setting quota information, getting quota format are all quotactl operations protected by s_umount semaphore held for reading grabbed in quotactl handler. This also fixes lockdep splat about possible deadlock during filesystem freezing where sync_filesystem() is called with page-faults already blocked but sync_filesystem() calls into dquot_writeback_dquots() which grabs dqonoff_mutex which ranks above i_mutex (vfs_load_quota_inode() grabs i_mutex under dqonoff_mutex) which clearly ranks below page fault freeze protection (e.g. via mmap_sem dependencies). The reported problem is not a real deadlock possibility since during quota on we check whether filesystem freezing is not in progress but still it is good to have this fixed. Reported-by: Ted Tso <tytso@mit.edu> Reported-by: Eric Whitney <enwlinux@gmail.com> Signed-off-by: Jan Kara <jack@suse.cz> |
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| .. | ||
| compat.c | ||
| dquot.c | ||
| Kconfig | ||
| kqid.c | ||
| Makefile | ||
| netlink.c | ||
| quota_tree.c | ||
| quota_tree.h | ||
| quota_v1.c | ||
| quota_v2.c | ||
| quota.c | ||
| quotaio_v1.h | ||
| quotaio_v2.h | ||