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[XFS] Move the XFS inode to the front of its hash list on a cache hit 

SGI Modid: xfs-linux:xfs-kern:21915a

Signed-off-by: Nathan Scott <nathans@sgi.com>
Signed-off-by: Christoph Hellwig <hch@sgi.com>
This commit is contained in:
Nathan Scott 2005-05-05 13:23:27 -07:00 committed by Christoph Hellwig
parent bfd4bda097
commit 71bce256bf
1 changed files with 50 additions and 1 deletions
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51
fs/xfs/xfs_iget.c
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@ -135,6 +135,40 @@ xfs_chash_free(xfs_mount_t *mp)
mp->m_chash = NULL;
}
/*
* Try to move an inode to the front of its hash list if possible
* (and if its not there already). Called right after obtaining
* the list version number and then dropping the read_lock on the
* hash list in question (which is done right after looking up the
* inode in question...).
*/
STATIC void
xfs_ihash_promote(
xfs_ihash_t *ih,
xfs_inode_t *ip,
ulong version)
{
xfs_inode_t *iq;
if ((ip->i_prevp != &ih->ih_next) && write_trylock(&ih->ih_lock)) {
if (likely(version == ih->ih_version)) {
/* remove from list */
if ((iq = ip->i_next)) {
iq->i_prevp = ip->i_prevp;
}
*ip->i_prevp = iq;
/* insert at list head */
iq = ih->ih_next;
iq->i_prevp = &ip->i_next;
ip->i_next = iq;
ip->i_prevp = &ih->ih_next;
ih->ih_next = ip;
}
write_unlock(&ih->ih_lock);
}
}
/*
* Look up an inode by number in the given file system.
* The inode is looked up in the hash table for the file system
@ -229,7 +263,9 @@ again:
XFS_STATS_INC(xs_ig_found);
ip->i_flags &= ~XFS_IRECLAIMABLE;
version = ih->ih_version;
read_unlock(&ih->ih_lock);
xfs_ihash_promote(ih, ip, version);
XFS_MOUNT_ILOCK(mp);
list_del_init(&ip->i_reclaim);
@ -259,8 +295,15 @@ again:
inode_vp, vp);
}
/*
* Inode cache hit: if ip is not at the front of
* its hash chain, move it there now.
* Do this with the lock held for update, but
* do statistics after releasing the lock.
*/
version = ih->ih_version;
read_unlock(&ih->ih_lock);
xfs_ihash_promote(ih, ip, version);
XFS_STATS_INC(xs_ig_found);
finish_inode:
@ -547,6 +590,7 @@ xfs_inode_incore(xfs_mount_t *mp,
{
xfs_ihash_t *ih;
xfs_inode_t *ip;
ulong version;
ih = XFS_IHASH(mp, ino);
read_lock(&ih->ih_lock);
@ -554,11 +598,15 @@ xfs_inode_incore(xfs_mount_t *mp,
if (ip->i_ino == ino) {
/*
* If we find it and tp matches, return it.
* Also move it to the front of the hash list
* if we find it and it is not already there.
* Otherwise break from the loop and return
* NULL.
*/
if (ip->i_transp == tp) {
version = ih->ih_version;
read_unlock(&ih->ih_lock);
xfs_ihash_promote(ih, ip, version);
return (ip);
}
break;
@ -685,6 +733,7 @@ xfs_iextract(
iq->i_prevp = ip->i_prevp;
}
*ip->i_prevp = iq;
ih->ih_version++;
write_unlock(&ih->ih_lock);
/*