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author | Attilio Rao <attilio@FreeBSD.org> | 2008-11-02 10:15:42 +0000 |
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committer | Attilio Rao <attilio@FreeBSD.org> | 2008-11-02 10:15:42 +0000 |
commit | 83b3bdbc8a62ff45142dfa354eb6eab7a81a0a6b (patch) | |
tree | 904da44fc29dcc675df2dfc69f644d6a90befc3c /sys/kern/vfs_lookup.c | |
parent | 0952268ecd3f2e5de535e97dcd9c94e4484edf85 (diff) | |
download | src-83b3bdbc8a62ff45142dfa354eb6eab7a81a0a6b.tar.gz src-83b3bdbc8a62ff45142dfa354eb6eab7a81a0a6b.zip |
Improve VFS locking:
- Implement real draining for vfs consumers by not relying on the
mnt_lock and using instead a refcount in order to keep track of lock
requesters.
- Due to the change above, remove the mnt_lock lockmgr because it is now
useless.
- Due to the change above, vfs_busy() is no more linked to a lockmgr.
Change so its KPI by removing the interlock argument and defining 2 new
flags for it: MBF_NOWAIT which basically replaces the LK_NOWAIT of the
old version (which was unlinked from the lockmgr alredy) and
MBF_MNTLSTLOCK which provides the ability to drop the mountlist_mtx
once the mnt interlock is held (ability still desired by most consumers).
- The stub used into vfs_mount_destroy(), that allows to override the
mnt_ref if running for more than 3 seconds, make it totally useless.
Remove it as it was thought to work into older versions.
If a problem of "refcount held never going away" should appear, we will
need to fix properly instead than trust on such hackish solution.
- Fix a bug where returning (with an error) from dounmount() was still
leaving the MNTK_MWAIT flag on even if it the waiters were actually
woken up. Just a place in vfs_mount_destroy() is left because it is
going to recycle the structure in any case, so it doesn't matter.
- Remove the markercnt refcount as it is useless.
This patch modifies VFS ABI and breaks KPI for vfs_busy() so manpages and
__FreeBSD_version will be modified accordingly.
Discussed with: kib
Tested by: pho
Notes
Notes:
svn path=/head/; revision=184554
Diffstat (limited to 'sys/kern/vfs_lookup.c')
-rw-r--r-- | sys/kern/vfs_lookup.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/sys/kern/vfs_lookup.c b/sys/kern/vfs_lookup.c index aa9cfbf9237b..f009dac4ad65 100644 --- a/sys/kern/vfs_lookup.c +++ b/sys/kern/vfs_lookup.c @@ -684,7 +684,7 @@ unionlookup: */ while (dp->v_type == VDIR && (mp = dp->v_mountedhere) && (cnp->cn_flags & NOCROSSMOUNT) == 0) { - if (vfs_busy(mp, 0, 0)) + if (vfs_busy(mp, 0)) continue; vput(dp); VFS_UNLOCK_GIANT(vfslocked); |