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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
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17
fs/xfs/xfs_dir2_sf.c
View File

@@ -812,9 +812,11 @@ xfs_dir2_sf_lookup(
{
xfs_inode_t *dp; /* incore directory inode */
int i; /* entry index */
int error;
xfs_dir2_sf_entry_t *sfep; /* shortform directory entry */
xfs_dir2_sf_t *sfp; /* shortform structure */
enum xfs_dacmp cmp; /* comparison result */
xfs_dir2_sf_entry_t *ci_sfep; /* case-insens. entry */
xfs_dir2_trace_args("sf_lookup", args);
xfs_dir2_sf_check(args);
@@ -852,6 +854,7 @@ xfs_dir2_sf_lookup(
/*
* Loop over all the entries trying to match ours.
*/
ci_sfep = NULL;
for (i = 0, sfep = xfs_dir2_sf_firstentry(sfp); i < sfp->hdr.count;
i++, sfep = xfs_dir2_sf_nextentry(sfp, sfep)) {
/*
@@ -867,19 +870,19 @@ xfs_dir2_sf_lookup(
xfs_dir2_sf_inumberp(sfep));
if (cmp == XFS_CMP_EXACT)
return XFS_ERROR(EEXIST);
ci_sfep = sfep;
}
}
ASSERT(args->op_flags & XFS_DA_OP_OKNOENT);
/*
* Here, we can only be doing a lookup (not a rename or replace).
* If a case-insensitive match was found earlier, return "found".
* If a case-insensitive match was not found, return ENOENT.
*/
if (args->cmpresult == XFS_CMP_CASE)
return XFS_ERROR(EEXIST);
/*
* Didn't find it.
*/
return XFS_ERROR(ENOENT);
if (!ci_sfep)
return XFS_ERROR(ENOENT);
/* otherwise process the CI match as required by the caller */
error = xfs_dir_cilookup_result(args, ci_sfep->name, ci_sfep->namelen);
return XFS_ERROR(error);
}
/*