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[XFS] Return case-insensitive match for dentry cache

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This implements the code to store the actual filename found during a
lookup in the dentry cache and to avoid multiple entries in the dcache
pointing to the same inode.

To avoid polluting the dcache, we implement a new directory inode
operations for lookup. xfs_vn_ci_lookup() stores the correct case name in
the dcache.

The "actual name" is only allocated and returned for a case- insensitive
match and not an actual match.

Another unusual interaction with the dcache is not storing negative
dentries like other filesystems doing a d_add(dentry, NULL) when an ENOENT
is returned. During the VFS lookup, if a dentry returned has no inode,
dput is called and ENOENT is returned. By not doing a d_add, this actually
removes it completely from the dcache to be reused. create/rename have to
be modified to support unhashed dentries being passed in.

SGI-PV: 981521
SGI-Modid: xfs-linux-melb:xfs-kern:31208a

Signed-off-by: Barry Naujok <bnaujok@sgi.com>
Signed-off-by: Christoph Hellwig <hch@infradead.org>
This commit is contained in:
Barry Naujok 2008-05-21 16:58:22 +10:00 • committed by Niv Sardi
parent 9403540c06
commit 384f3ced07
12 changed files with 147 additions and 30 deletions
Download patch file Download diff file Expand all files Collapse all files

19
fs/xfs/xfs_vnodeops.c
View file

@ -1610,12 +1610,18 @@ xfs_inactive(
return VN_INACTIVE_CACHE;
}
/*
* Lookups up an inode from "name". If ci_name is not NULL, then a CI match
* is allowed, otherwise it has to be an exact match. If a CI match is found,
* ci_name->name will point to a the actual name (caller must free) or
* will be set to NULL if an exact match is found.
*/
int
xfs_lookup(
xfs_inode_t *dp,
struct xfs_name *name,
xfs_inode_t **ipp)
xfs_inode_t **ipp,
struct xfs_name *ci_name)
{
xfs_ino_t inum;
int error;
@ -1627,7 +1633,7 @@ xfs_lookup(
return XFS_ERROR(EIO);
lock_mode = xfs_ilock_map_shared(dp);
error = xfs_dir_lookup(NULL, dp, name, &inum);
error = xfs_dir_lookup(NULL, dp, name, &inum, ci_name);
xfs_iunlock_map_shared(dp, lock_mode);
if (error)
@ -1635,12 +1641,15 @@ xfs_lookup(
error = xfs_iget(dp->i_mount, NULL, inum, 0, 0, ipp, 0);
if (error)
goto out;
goto out_free_name;
xfs_itrace_ref(*ipp);
return 0;
out:
out_free_name:
if (ci_name)
kmem_free(ci_name->name);
out:
*ipp = NULL;
return error;
}