[XFS] Return case-insensitive match for dentry cache
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>
diff --git a/fs/xfs/xfs_dir2.c b/fs/xfs/xfs_dir2.c
index 3387acd..882609c 100644
--- a/fs/xfs/xfs_dir2.c
+++ b/fs/xfs/xfs_dir2.c
@@ -193,14 +193,43 @@
}
/*
- * Lookup a name in a directory, give back the inode number.
+ * If doing a CI lookup and case-insensitive match, dup actual name into
+ * args.value. Return EEXIST for success (ie. name found) or an error.
*/
int
+xfs_dir_cilookup_result(
+ struct xfs_da_args *args,
+ const char *name,
+ int len)
+{
+ if (args->cmpresult == XFS_CMP_DIFFERENT)
+ return ENOENT;
+ if (args->cmpresult != XFS_CMP_CASE ||
+ !(args->op_flags & XFS_DA_OP_CILOOKUP))
+ return EEXIST;
+
+ args->value = kmem_alloc(len, KM_MAYFAIL);
+ if (!args->value)
+ return ENOMEM;
+
+ memcpy(args->value, name, len);
+ args->valuelen = len;
+ return EEXIST;
+}
+
+/*
+ * Lookup a name in a directory, give back the inode number.
+ * If ci_name is not NULL, returns the actual name in ci_name if it differs
+ * to name, or ci_name->name is set to NULL for an exact match.
+ */
+
+int
xfs_dir_lookup(
xfs_trans_t *tp,
xfs_inode_t *dp,
struct xfs_name *name,
- xfs_ino_t *inum) /* out: inode number */
+ xfs_ino_t *inum, /* out: inode number */
+ struct xfs_name *ci_name) /* out: actual name if CI match */
{
xfs_da_args_t args;
int rval;
@@ -217,6 +246,8 @@
args.whichfork = XFS_DATA_FORK;
args.trans = tp;
args.op_flags = XFS_DA_OP_OKNOENT;
+ if (ci_name)
+ args.op_flags |= XFS_DA_OP_CILOOKUP;
args.cmpresult = XFS_CMP_DIFFERENT;
if (dp->i_d.di_format == XFS_DINODE_FMT_LOCAL)
@@ -233,8 +264,13 @@
rval = xfs_dir2_node_lookup(&args);
if (rval == EEXIST)
rval = 0;
- if (rval == 0)
+ if (!rval) {
*inum = args.inumber;
+ if (ci_name) {
+ ci_name->name = args.value;
+ ci_name->len = args.valuelen;
+ }
+ }
return rval;
}