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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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16
fs/xfs/xfs_dir2_node.c
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@@ -549,7 +549,7 @@ xfs_dir2_leafn_lookup_for_entry(
xfs_dir2_data_entry_t *dep; /* data block entry */
xfs_inode_t *dp; /* incore directory inode */
int error; /* error return value */
int di; /* data entry index */
int di = -1; /* data entry index */
int index; /* leaf entry index */
xfs_dir2_leaf_t *leaf; /* leaf structure */
xfs_dir2_leaf_entry_t *lep; /* leaf entry */
@@ -577,6 +577,7 @@ xfs_dir2_leafn_lookup_for_entry(
if (state->extravalid) {
curbp = state->extrablk.bp;
curdb = state->extrablk.blkno;
di = state->extrablk.index;
}
/*
* Loop over leaf entries with the right hash value.
@@ -637,7 +638,6 @@ xfs_dir2_leafn_lookup_for_entry(
}
/* Didn't find an exact match. */
error = ENOENT;
di = -1;
ASSERT(index == be16_to_cpu(leaf->hdr.count) ||
(args->op_flags & XFS_DA_OP_OKNOENT));
out:
@@ -652,7 +652,7 @@ out:
state->extravalid = 0;
}
/*
* Return the index, that will be the insertion point.
* Return the index, that will be the deletion point for remove/replace.
*/
*indexp = index;
return XFS_ERROR(error);
@@ -1820,8 +1820,14 @@ xfs_dir2_node_lookup(
error = xfs_da_node_lookup_int(state, &rval);
if (error)
rval = error;
else if (rval == ENOENT && args->cmpresult == XFS_CMP_CASE)
rval = EEXIST; /* a case-insensitive match was found */
else if (rval == ENOENT && args->cmpresult == XFS_CMP_CASE) {
/* If a CI match, dup the actual name and return EEXIST */
xfs_dir2_data_entry_t *dep;
dep = (xfs_dir2_data_entry_t *)((char *)state->extrablk.bp->
data + state->extrablk.index);
rval = xfs_dir_cilookup_result(args, dep->name, dep->namelen);
}
/*
* Release the btree blocks and leaf block.
*/