[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>

12 files changed, 146 insertions, 29 deletions

diff --git a/fs/xfs/linux-2.6/xfs_export.c b/fs/xfs/linux-2.6/xfs_export.c
index c672b3238b14..987fe84f7b13 100644
--- a/fs/xfs/linux-2.6/xfs_export.c
+++ b/fs/xfs/linux-2.6/xfs_export.c
@@ -215,7 +215,7 @@ xfs_fs_get_parent(
         struct xfs_inode        *cip;
         struct dentry           *parent;
 
-        error = xfs_lookup(XFS_I(child->d_inode), &xfs_name_dotdot, &cip);
+        error = xfs_lookup(XFS_I(child->d_inode), &xfs_name_dotdot, &cip, NULL);
         if (unlikely(error))
                 return ERR_PTR(-error);
 
diff --git a/fs/xfs/linux-2.6/xfs_iops.c b/fs/xfs/linux-2.6/xfs_iops.c
index 13b6cfd366c2..9f0f8ee8d44d 100644
--- a/fs/xfs/linux-2.6/xfs_iops.c
+++ b/fs/xfs/linux-2.6/xfs_iops.c
@@ -382,7 +382,7 @@ xfs_vn_lookup(
                 return ERR_PTR(-ENAMETOOLONG);
 
         xfs_dentry_to_name(&name, dentry);
-        error = xfs_lookup(XFS_I(dir), &name, &cip);
+        error = xfs_lookup(XFS_I(dir), &name, &cip, NULL);
         if (unlikely(error)) {
                 if (unlikely(error != ENOENT))
                         return ERR_PTR(-error);
@@ -393,6 +393,42 @@ xfs_vn_lookup(
         return d_splice_alias(cip->i_vnode, dentry);
 }
 
+STATIC struct dentry *
+xfs_vn_ci_lookup(
+        struct inode    *dir,
+        struct dentry   *dentry,
+        struct nameidata *nd)
+{
+        struct xfs_inode *ip;
+        struct xfs_name xname;
+        struct xfs_name ci_name;
+        struct qstr     dname;
+        int             error;
+
+        if (dentry->d_name.len >= MAXNAMELEN)
+                return ERR_PTR(-ENAMETOOLONG);
+
+        xfs_dentry_to_name(&xname, dentry);
+        error = xfs_lookup(XFS_I(dir), &xname, &ip, &ci_name);
+        if (unlikely(error)) {
+                if (unlikely(error != ENOENT))
+                        return ERR_PTR(-error);
+                d_add(dentry, NULL);
+                return NULL;
+        }
+
+        /* if exact match, just splice and exit */
+        if (!ci_name.name)
+                return d_splice_alias(ip->i_vnode, dentry);
+
+        /* else case-insensitive match... */
+        dname.name = ci_name.name;
+        dname.len = ci_name.len;
+        dentry = d_add_ci(ip->i_vnode, dentry, &dname);
+        kmem_free(ci_name.name);
+        return dentry;
+}
+
 STATIC int
 xfs_vn_link(
         struct dentry   *old_dentry,
@@ -892,6 +928,25 @@ const struct inode_operations xfs_dir_inode_operations = {
         .removexattr            = xfs_vn_removexattr,
 };
 
+const struct inode_operations xfs_dir_ci_inode_operations = {
+        .create                 = xfs_vn_create,
+        .lookup                 = xfs_vn_ci_lookup,
+        .link                   = xfs_vn_link,
+        .unlink                 = xfs_vn_unlink,
+        .symlink                = xfs_vn_symlink,
+        .mkdir                  = xfs_vn_mkdir,
+        .rmdir                  = xfs_vn_rmdir,
+        .mknod                  = xfs_vn_mknod,
+        .rename                 = xfs_vn_rename,
+        .permission             = xfs_vn_permission,
+        .getattr                = xfs_vn_getattr,
+        .setattr                = xfs_vn_setattr,
+        .setxattr               = xfs_vn_setxattr,
+        .getxattr               = xfs_vn_getxattr,
+        .listxattr              = xfs_vn_listxattr,
+        .removexattr            = xfs_vn_removexattr,
+};
+
 const struct inode_operations xfs_symlink_inode_operations = {
         .readlink               = generic_readlink,
         .follow_link            = xfs_vn_follow_link,
diff --git a/fs/xfs/linux-2.6/xfs_iops.h b/fs/xfs/linux-2.6/xfs_iops.h
index 14d0deb7afff..3b4df5863e4a 100644
--- a/fs/xfs/linux-2.6/xfs_iops.h
+++ b/fs/xfs/linux-2.6/xfs_iops.h
@@ -20,6 +20,7 @@
 
 extern const struct inode_operations xfs_inode_operations;
 extern const struct inode_operations xfs_dir_inode_operations;
+extern const struct inode_operations xfs_dir_ci_inode_operations;
 extern const struct inode_operations xfs_symlink_inode_operations;
 
 extern const struct file_operations xfs_file_operations;
diff --git a/fs/xfs/xfs_da_btree.h b/fs/xfs/xfs_da_btree.h
index 8face64c11fb..8be0b00ede9a 100644
--- a/fs/xfs/xfs_da_btree.h
+++ b/fs/xfs/xfs_da_btree.h
@@ -143,6 +143,7 @@ typedef struct xfs_da_args {
 #define XFS_DA_OP_RENAME        0x0002  /* this is an atomic rename op */
 #define XFS_DA_OP_ADDNAME       0x0004  /* this is an add operation */
 #define XFS_DA_OP_OKNOENT       0x0008  /* lookup/add op, ENOENT ok, else die */
+#define XFS_DA_OP_CILOOKUP      0x0010  /* lookup to return CI name if found */
 
 /*
  * Structure to describe buffer(s) for a block.
diff --git a/fs/xfs/xfs_dir2.c b/fs/xfs/xfs_dir2.c
index 3387acd3e471..882609c699c8 100644
--- a/fs/xfs/xfs_dir2.c
+++ b/fs/xfs/xfs_dir2.c
@@ -193,14 +193,43 @@ xfs_dir_createname(
 }
 
 /*
+ * 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 @@ xfs_dir_lookup(
         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 @@ xfs_dir_lookup(
                 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;
 }
 
diff --git a/fs/xfs/xfs_dir2.h b/fs/xfs/xfs_dir2.h
index 6392f939029f..1d9ef96f33aa 100644
--- a/fs/xfs/xfs_dir2.h
+++ b/fs/xfs/xfs_dir2.h
@@ -74,7 +74,8 @@ extern int xfs_dir_createname(struct xfs_trans *tp, struct xfs_inode *dp,
                                 xfs_fsblock_t *first,
                                 struct xfs_bmap_free *flist, xfs_extlen_t tot);
 extern int xfs_dir_lookup(struct xfs_trans *tp, struct xfs_inode *dp,
-                                struct xfs_name *name, xfs_ino_t *inum);
+                                struct xfs_name *name, xfs_ino_t *inum,
+                                struct xfs_name *ci_name);
 extern int xfs_dir_removename(struct xfs_trans *tp, struct xfs_inode *dp,
                                 struct xfs_name *name, xfs_ino_t ino,
                                 xfs_fsblock_t *first,
@@ -99,4 +100,7 @@ extern int xfs_dir2_isleaf(struct xfs_trans *tp, struct xfs_inode *dp,
 extern int xfs_dir2_shrink_inode(struct xfs_da_args *args, xfs_dir2_db_t db,
                                 struct xfs_dabuf *bp);
 
+extern int xfs_dir_cilookup_result(struct xfs_da_args *args, const char *name,
+                                int len);
+
 #endif  /* __XFS_DIR2_H__ */
diff --git a/fs/xfs/xfs_dir2_block.c b/fs/xfs/xfs_dir2_block.c
index dee225918db2..e2fa0a1d8e96 100644
--- a/fs/xfs/xfs_dir2_block.c
+++ b/fs/xfs/xfs_dir2_block.c
@@ -610,14 +610,15 @@ xfs_dir2_block_lookup(
         /*
          * Get the offset from the leaf entry, to point to the data.
          */
-        dep = (xfs_dir2_data_entry_t *)
-              ((char *)block + xfs_dir2_dataptr_to_off(mp, be32_to_cpu(blp[ent].address)));
+        dep = (xfs_dir2_data_entry_t *)((char *)block +
+                xfs_dir2_dataptr_to_off(mp, be32_to_cpu(blp[ent].address)));
         /*
-         * Fill in inode number, release the block.
+         * Fill in inode number, CI name if appropriate, release the block.
          */
         args->inumber = be64_to_cpu(dep->inumber);
+        error = xfs_dir_cilookup_result(args, dep->name, dep->namelen);
         xfs_da_brelse(args->trans, bp);
-        return XFS_ERROR(EEXIST);
+        return XFS_ERROR(error);
 }
 
 /*
diff --git a/fs/xfs/xfs_dir2_leaf.c b/fs/xfs/xfs_dir2_leaf.c
index 2ebbed4f1b0d..f110242d6dfc 100644
--- a/fs/xfs/xfs_dir2_leaf.c
+++ b/fs/xfs/xfs_dir2_leaf.c
@@ -1299,12 +1299,13 @@ xfs_dir2_leaf_lookup(
               ((char *)dbp->data +
                xfs_dir2_dataptr_to_off(dp->i_mount, be32_to_cpu(lep->address)));
         /*
-         * Return the found inode number.
+         * Return the found inode number & CI name if appropriate
          */
         args->inumber = be64_to_cpu(dep->inumber);
+        error = xfs_dir_cilookup_result(args, dep->name, dep->namelen);
         xfs_da_brelse(tp, dbp);
         xfs_da_brelse(tp, lbp);
-        return XFS_ERROR(EEXIST);
+        return XFS_ERROR(error);
 }
 
 /*
diff --git a/fs/xfs/xfs_dir2_node.c b/fs/xfs/xfs_dir2_node.c
index c71cff85950c..1b5430223461 100644
--- a/fs/xfs/xfs_dir2_node.c
+++ b/fs/xfs/xfs_dir2_node.c
@@ -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.
          */
diff --git a/fs/xfs/xfs_dir2_sf.c b/fs/xfs/xfs_dir2_sf.c
index 9409fd3e565f..b46af0013ec9 100644
--- a/fs/xfs/xfs_dir2_sf.c
+++ b/fs/xfs/xfs_dir2_sf.c
@@ -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);
 }
 
 /*
diff --git a/fs/xfs/xfs_vnodeops.c b/fs/xfs/xfs_vnodeops.c
index 9b8b87fcd4ec..b6a065eb25a5 100644
--- a/fs/xfs/xfs_vnodeops.c
+++ b/fs/xfs/xfs_vnodeops.c
@@ -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;
 }
diff --git a/fs/xfs/xfs_vnodeops.h b/fs/xfs/xfs_vnodeops.h
index 57335ba4ce53..7e9a8b241f21 100644
--- a/fs/xfs/xfs_vnodeops.h
+++ b/fs/xfs/xfs_vnodeops.h
@@ -22,7 +22,7 @@ int xfs_fsync(struct xfs_inode *ip);
 int xfs_release(struct xfs_inode *ip);
 int xfs_inactive(struct xfs_inode *ip);
 int xfs_lookup(struct xfs_inode *dp, struct xfs_name *name,
-                struct xfs_inode **ipp);
+                struct xfs_inode **ipp, struct xfs_name *ci_name);
 int xfs_create(struct xfs_inode *dp, struct xfs_name *name, mode_t mode,
                 xfs_dev_t rdev, struct xfs_inode **ipp, struct cred *credp);
 int xfs_remove(struct xfs_inode *dp, struct xfs_name *name,