[PATCH] get rid of on-stack fake dentry in ext3_get_parent()
Al Viro [Sun, 24 Aug 2008 11:26:48 +0000 (07:26 -0400)]
Better pass parent and qstr to ext3_find_entry() explicitly than
use such kludges, especially since the stack footprint is nasty
enough and we have every chance to be deep in call chain.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/ext3/namei.c

index 880b544..3e5edc9 100644 (file)
@@ -159,7 +159,7 @@ static void dx_set_count (struct dx_entry *entries, unsigned value);
 static void dx_set_limit (struct dx_entry *entries, unsigned value);
 static unsigned dx_root_limit (struct inode *dir, unsigned infosize);
 static unsigned dx_node_limit (struct inode *dir);
-static struct dx_frame *dx_probe(struct dentry *dentry,
+static struct dx_frame *dx_probe(struct qstr *entry,
                                 struct inode *dir,
                                 struct dx_hash_info *hinfo,
                                 struct dx_frame *frame,
@@ -176,8 +176,9 @@ static int ext3_htree_next_block(struct inode *dir, __u32 hash,
                                 struct dx_frame *frame,
                                 struct dx_frame *frames,
                                 __u32 *start_hash);
-static struct buffer_head * ext3_dx_find_entry(struct dentry *dentry,
-                      struct ext3_dir_entry_2 **res_dir, int *err);
+static struct buffer_head * ext3_dx_find_entry(struct inode *dir,
+                       struct qstr *entry, struct ext3_dir_entry_2 **res_dir,
+                       int *err);
 static int ext3_dx_add_entry(handle_t *handle, struct dentry *dentry,
                             struct inode *inode);
 
@@ -342,7 +343,7 @@ struct stats dx_show_entries(struct dx_hash_info *hinfo, struct inode *dir,
  * back to userspace.
  */
 static struct dx_frame *
-dx_probe(struct dentry *dentry, struct inode *dir,
+dx_probe(struct qstr *entry, struct inode *dir,
         struct dx_hash_info *hinfo, struct dx_frame *frame_in, int *err)
 {
        unsigned count, indirect;
@@ -353,8 +354,6 @@ dx_probe(struct dentry *dentry, struct inode *dir,
        u32 hash;
 
        frame->bh = NULL;
-       if (dentry)
-               dir = dentry->d_parent->d_inode;
        if (!(bh = ext3_bread (NULL,dir, 0, 0, err)))
                goto fail;
        root = (struct dx_root *) bh->b_data;
@@ -370,8 +369,8 @@ dx_probe(struct dentry *dentry, struct inode *dir,
        }
        hinfo->hash_version = root->info.hash_version;
        hinfo->seed = EXT3_SB(dir->i_sb)->s_hash_seed;
-       if (dentry)
-               ext3fs_dirhash(dentry->d_name.name, dentry->d_name.len, hinfo);
+       if (entry)
+               ext3fs_dirhash(entry->name, entry->len, hinfo);
        hash = hinfo->hash;
 
        if (root->info.unused_flags & 1) {
@@ -803,15 +802,15 @@ static inline int ext3_match (int len, const char * const name,
  */
 static inline int search_dirblock(struct buffer_head * bh,
                                  struct inode *dir,
-                                 struct dentry *dentry,
+                                 struct qstr *child,
                                  unsigned long offset,
                                  struct ext3_dir_entry_2 ** res_dir)
 {
        struct ext3_dir_entry_2 * de;
        char * dlimit;
        int de_len;
-       const char *name = dentry->d_name.name;
-       int namelen = dentry->d_name.len;
+       const char *name = child->name;
+       int namelen = child->len;
 
        de = (struct ext3_dir_entry_2 *) bh->b_data;
        dlimit = bh->b_data + dir->i_sb->s_blocksize;
@@ -850,8 +849,9 @@ static inline int search_dirblock(struct buffer_head * bh,
  * The returned buffer_head has ->b_count elevated.  The caller is expected
  * to brelse() it when appropriate.
  */
-static struct buffer_head * ext3_find_entry (struct dentry *dentry,
-                                       struct ext3_dir_entry_2 ** res_dir)
+static struct buffer_head *ext3_find_entry(struct inode *dir,
+                                       struct qstr *entry,
+                                       struct ext3_dir_entry_2 **res_dir)
 {
        struct super_block * sb;
        struct buffer_head * bh_use[NAMEI_RA_SIZE];
@@ -863,16 +863,15 @@ static struct buffer_head * ext3_find_entry (struct dentry *dentry,
                                   buffer */
        int num = 0;
        int nblocks, i, err;
-       struct inode *dir = dentry->d_parent->d_inode;
        int namelen;
 
        *res_dir = NULL;
        sb = dir->i_sb;
-       namelen = dentry->d_name.len;
+       namelen = entry->len;
        if (namelen > EXT3_NAME_LEN)
                return NULL;
        if (is_dx(dir)) {
-               bh = ext3_dx_find_entry(dentry, res_dir, &err);
+               bh = ext3_dx_find_entry(dir, entry, res_dir, &err);
                /*
                 * On success, or if the error was file not found,
                 * return.  Otherwise, fall back to doing a search the
@@ -923,7 +922,7 @@ restart:
                        brelse(bh);
                        goto next;
                }
-               i = search_dirblock(bh, dir, dentry,
+               i = search_dirblock(bh, dir, entry,
                            block << EXT3_BLOCK_SIZE_BITS(sb), res_dir);
                if (i == 1) {
                        EXT3_I(dir)->i_dir_start_lookup = block;
@@ -957,8 +956,9 @@ cleanup_and_exit:
        return ret;
 }
 
-static struct buffer_head * ext3_dx_find_entry(struct dentry *dentry,
-                      struct ext3_dir_entry_2 **res_dir, int *err)
+static struct buffer_head * ext3_dx_find_entry(struct inode *dir,
+                       struct qstr *entry, struct ext3_dir_entry_2 **res_dir,
+                       int *err)
 {
        struct super_block * sb;
        struct dx_hash_info     hinfo;
@@ -968,14 +968,13 @@ static struct buffer_head * ext3_dx_find_entry(struct dentry *dentry,
        struct buffer_head *bh;
        unsigned long block;
        int retval;
-       int namelen = dentry->d_name.len;
-       const u8 *name = dentry->d_name.name;
-       struct inode *dir = dentry->d_parent->d_inode;
+       int namelen = entry->len;
+       const u8 *name = entry->name;
 
        sb = dir->i_sb;
        /* NFS may look up ".." - look at dx_root directory block */
-       if (namelen > 2 || name[0] != '.'||(name[1] != '.' && name[1] != '\0')){
-               if (!(frame = dx_probe(dentry, NULL, &hinfo, frames, err)))
+       if (namelen > 2 || name[0] != '.'|| (namelen == 2 && name[1] != '.')) {
+               if (!(frame = dx_probe(entry, dir, &hinfo, frames, err)))
                        return NULL;
        } else {
                frame = frames;
@@ -1036,7 +1035,7 @@ static struct dentry *ext3_lookup(struct inode * dir, struct dentry *dentry, str
        if (dentry->d_name.len > EXT3_NAME_LEN)
                return ERR_PTR(-ENAMETOOLONG);
 
-       bh = ext3_find_entry(dentry, &de);
+       bh = ext3_find_entry(dir, &dentry->d_name, &de);
        inode = NULL;
        if (bh) {
                unsigned long ino = le32_to_cpu(de->inode);
@@ -1057,15 +1056,11 @@ static struct dentry *ext3_lookup(struct inode * dir, struct dentry *dentry, str
 struct dentry *ext3_get_parent(struct dentry *child)
 {
        unsigned long ino;
-       struct dentry dotdot;
+       struct qstr dotdot = {.name = "..", .len = 2};
        struct ext3_dir_entry_2 * de;
        struct buffer_head *bh;
 
-       dotdot.d_name.name = "..";
-       dotdot.d_name.len = 2;
-       dotdot.d_parent = child; /* confusing, isn't it! */
-
-       bh = ext3_find_entry(&dotdot, &de);
+       bh = ext3_find_entry(child->d_inode, &dotdot, &de);
        if (!bh)
                return ERR_PTR(-ENOENT);
        ino = le32_to_cpu(de->inode);
@@ -1491,7 +1486,7 @@ static int ext3_dx_add_entry(handle_t *handle, struct dentry *dentry,
        struct ext3_dir_entry_2 *de;
        int err;
 
-       frame = dx_probe(dentry, NULL, &hinfo, frames, &err);
+       frame = dx_probe(&dentry->d_name, dir, &hinfo, frames, &err);
        if (!frame)
                return err;
        entries = frame->entries;
@@ -2044,7 +2039,7 @@ static int ext3_rmdir (struct inode * dir, struct dentry *dentry)
                return PTR_ERR(handle);
 
        retval = -ENOENT;
-       bh = ext3_find_entry (dentry, &de);
+       bh = ext3_find_entry(dir, &dentry->d_name, &de);
        if (!bh)
                goto end_rmdir;
 
@@ -2106,7 +2101,7 @@ static int ext3_unlink(struct inode * dir, struct dentry *dentry)
                handle->h_sync = 1;
 
        retval = -ENOENT;
-       bh = ext3_find_entry (dentry, &de);
+       bh = ext3_find_entry(dir, &dentry->d_name, &de);
        if (!bh)
                goto end_unlink;
 
@@ -2264,7 +2259,7 @@ static int ext3_rename (struct inode * old_dir, struct dentry *old_dentry,
        if (IS_DIRSYNC(old_dir) || IS_DIRSYNC(new_dir))
                handle->h_sync = 1;
 
-       old_bh = ext3_find_entry (old_dentry, &old_de);
+       old_bh = ext3_find_entry(old_dir, &old_dentry->d_name, &old_de);
        /*
         *  Check for inode number is _not_ due to possible IO errors.
         *  We might rmdir the source, keep it as pwd of some process
@@ -2277,7 +2272,7 @@ static int ext3_rename (struct inode * old_dir, struct dentry *old_dentry,
                goto end_rename;
 
        new_inode = new_dentry->d_inode;
-       new_bh = ext3_find_entry (new_dentry, &new_de);
+       new_bh = ext3_find_entry(new_dir, &new_dentry->d_name, &new_de);
        if (new_bh) {
                if (!new_inode) {
                        brelse (new_bh);
@@ -2343,7 +2338,8 @@ static int ext3_rename (struct inode * old_dir, struct dentry *old_dentry,
                struct buffer_head *old_bh2;
                struct ext3_dir_entry_2 *old_de2;
 
-               old_bh2 = ext3_find_entry(old_dentry, &old_de2);
+               old_bh2 = ext3_find_entry(old_dir, &old_dentry->d_name,
+                                         &old_de2);
                if (old_bh2) {
                        retval = ext3_delete_entry(handle, old_dir,
                                                   old_de2, old_bh2);