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Don't hold on to the afs_xvcache lock while creating a symlink

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Holding the afs_xvcache lock over the RPC while creating a symlink is a
severe blow to performance as look-ups from other tasks likely
require the lock. Drop the lock and rely solely on the fileserver
to detect a clash with a same entry created simultaneously.

Change-Id: Ia6de353bd9dc003addf5f3be7a8f3e769247a513
Reviewed-on: http://gerrit.openafs.org/2233
Tested-by: Derrick Brashear <shadow@dementia.org>
Reviewed-by: Derrick Brashear <shadow@dementia.org>
This commit is contained in:
Rainer Toebbicke 2010-06-21 12:02:46 +02:00 committed by Derrick Brashear
parent bd3f8adfe0
commit c39aee89c0
1 changed files with 6 additions and 3 deletions
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9
src/afs/VNOPS/afs_vnop_symlink.c
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@ -153,8 +153,9 @@ afs_symlink(OSI_VC_DECL(adp), char *aname, struct vattr *attrs,
ObtainWriteLock(&adp->lock, 156); ObtainWriteLock(&adp->lock, 156);
if (tdc) if (tdc)
ObtainWriteLock(&tdc->lock, 636); ObtainWriteLock(&tdc->lock, 636);
ObtainSharedLock(&afs_xvcache, 17); /* prevent others from creating this entry */ /* No further locks: if the SymLink succeeds, it does not matter what happens
/* XXX Pay attention to afs_xvcache around the whole thing!! XXX */ * to our local copy of the directory. If somebody tampers with it in the meantime,
* the copy will be invalidated */
if (!AFS_IS_DISCON_RW) { if (!AFS_IS_DISCON_RW) {
do { do {
tc = afs_Conn(&adp->f.fid, &treq, SHARED_LOCK); tc = afs_Conn(&adp->f.fid, &treq, SHARED_LOCK);
@ -195,7 +196,7 @@ afs_symlink(OSI_VC_DECL(adp), char *aname, struct vattr *attrs,
#endif #endif
} }
UpgradeSToWLock(&afs_xvcache, 40); ObtainWriteLock(&afs_xvcache, 40);
if (code) { if (code) {
if (code < 0) { if (code < 0) {
ObtainWriteLock(&afs_xcbhash, 499); ObtainWriteLock(&afs_xcbhash, 499);
@ -216,6 +217,8 @@ afs_symlink(OSI_VC_DECL(adp), char *aname, struct vattr *attrs,
if (AFS_IS_DISCON_RW || afs_LocalHero(adp, tdc, &OutDirStatus, 1)) { if (AFS_IS_DISCON_RW || afs_LocalHero(adp, tdc, &OutDirStatus, 1)) {
/* we can do it locally */ /* we can do it locally */
ObtainWriteLock(&afs_xdcache, 293); ObtainWriteLock(&afs_xdcache, 293);
/* If the following fails because the name has been created in the meantime, the
* directory is out-of-date - the file server knows best! */
code = afs_dir_Create(tdc, aname, &newFid.Fid); code = afs_dir_Create(tdc, aname, &newFid.Fid);
ReleaseWriteLock(&afs_xdcache); ReleaseWriteLock(&afs_xdcache);
if (code && !AFS_IS_DISCON_RW) { if (code && !AFS_IS_DISCON_RW) {