ext4: Don't use 'struct dentry' for internal lookups
This is a port of a patch from Linus which fixes a 200+ byte stack usage problem in ext4_get_parent(). It's more efficient to pass down only the actual parts of the dentry that matter: the parent inode and the name, instead of allocating a struct dentry on the stack. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
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914258bf2c
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f702ba0fd7
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@ -159,7 +159,7 @@ static void dx_set_count(struct dx_entry *entries, unsigned value);
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static void dx_set_limit(struct dx_entry *entries, unsigned value);
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static unsigned dx_root_limit(struct inode *dir, unsigned infosize);
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static unsigned dx_node_limit(struct inode *dir);
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static struct dx_frame *dx_probe(struct dentry *dentry,
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static struct dx_frame *dx_probe(const struct qstr *d_name,
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struct inode *dir,
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struct dx_hash_info *hinfo,
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struct dx_frame *frame,
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@ -177,8 +177,10 @@ static int ext4_htree_next_block(struct inode *dir, __u32 hash,
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struct dx_frame *frame,
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struct dx_frame *frames,
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__u32 *start_hash);
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static struct buffer_head * ext4_dx_find_entry(struct dentry *dentry,
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struct ext4_dir_entry_2 **res_dir, int *err);
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static struct buffer_head * ext4_dx_find_entry(struct inode *dir,
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const struct qstr *d_name,
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struct ext4_dir_entry_2 **res_dir,
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int *err);
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static int ext4_dx_add_entry(handle_t *handle, struct dentry *dentry,
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struct inode *inode);
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@ -345,7 +347,7 @@ struct stats dx_show_entries(struct dx_hash_info *hinfo, struct inode *dir,
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* back to userspace.
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*/
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static struct dx_frame *
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dx_probe(struct dentry *dentry, struct inode *dir,
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dx_probe(const struct qstr *d_name, struct inode *dir,
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struct dx_hash_info *hinfo, struct dx_frame *frame_in, int *err)
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{
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unsigned count, indirect;
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@ -356,8 +358,6 @@ dx_probe(struct dentry *dentry, struct inode *dir,
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u32 hash;
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frame->bh = NULL;
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if (dentry)
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dir = dentry->d_parent->d_inode;
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if (!(bh = ext4_bread (NULL,dir, 0, 0, err)))
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goto fail;
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root = (struct dx_root *) bh->b_data;
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@ -373,8 +373,8 @@ dx_probe(struct dentry *dentry, struct inode *dir,
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}
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hinfo->hash_version = root->info.hash_version;
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hinfo->seed = EXT4_SB(dir->i_sb)->s_hash_seed;
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if (dentry)
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ext4fs_dirhash(dentry->d_name.name, dentry->d_name.len, hinfo);
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if (d_name)
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ext4fs_dirhash(d_name->name, d_name->len, hinfo);
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hash = hinfo->hash;
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if (root->info.unused_flags & 1) {
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@ -649,7 +649,7 @@ int ext4_htree_fill_tree(struct file *dir_file, __u32 start_hash,
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}
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hinfo.hash = start_hash;
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hinfo.minor_hash = 0;
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frame = dx_probe(NULL, dir_file->f_path.dentry->d_inode, &hinfo, frames, &err);
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frame = dx_probe(NULL, dir, &hinfo, frames, &err);
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if (!frame)
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return err;
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@ -805,15 +805,15 @@ static inline int ext4_match (int len, const char * const name,
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*/
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static inline int search_dirblock(struct buffer_head *bh,
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struct inode *dir,
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struct dentry *dentry,
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const struct qstr *d_name,
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unsigned long offset,
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struct ext4_dir_entry_2 ** res_dir)
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{
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struct ext4_dir_entry_2 * de;
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char * dlimit;
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int de_len;
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const char *name = dentry->d_name.name;
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int namelen = dentry->d_name.len;
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const char *name = d_name->name;
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int namelen = d_name->len;
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de = (struct ext4_dir_entry_2 *) bh->b_data;
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dlimit = bh->b_data + dir->i_sb->s_blocksize;
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@ -852,7 +852,8 @@ static inline int search_dirblock(struct buffer_head *bh,
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* The returned buffer_head has ->b_count elevated. The caller is expected
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* to brelse() it when appropriate.
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*/
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static struct buffer_head * ext4_find_entry (struct dentry *dentry,
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static struct buffer_head * ext4_find_entry (struct inode *dir,
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const struct qstr *d_name,
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struct ext4_dir_entry_2 ** res_dir)
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{
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struct super_block *sb;
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@ -866,16 +867,15 @@ static struct buffer_head * ext4_find_entry (struct dentry *dentry,
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int num = 0;
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ext4_lblk_t nblocks;
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int i, err;
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struct inode *dir = dentry->d_parent->d_inode;
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int namelen;
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*res_dir = NULL;
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sb = dir->i_sb;
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namelen = dentry->d_name.len;
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namelen = d_name->len;
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if (namelen > EXT4_NAME_LEN)
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return NULL;
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if (is_dx(dir)) {
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bh = ext4_dx_find_entry(dentry, res_dir, &err);
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bh = ext4_dx_find_entry(dir, d_name, res_dir, &err);
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/*
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* On success, or if the error was file not found,
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* return. Otherwise, fall back to doing a search the
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@ -928,7 +928,7 @@ restart:
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brelse(bh);
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goto next;
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}
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i = search_dirblock(bh, dir, dentry,
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i = search_dirblock(bh, dir, d_name,
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block << EXT4_BLOCK_SIZE_BITS(sb), res_dir);
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if (i == 1) {
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EXT4_I(dir)->i_dir_start_lookup = block;
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@ -962,7 +962,7 @@ cleanup_and_exit:
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return ret;
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}
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static struct buffer_head * ext4_dx_find_entry(struct dentry *dentry,
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static struct buffer_head * ext4_dx_find_entry(struct inode *dir, const struct qstr *d_name,
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struct ext4_dir_entry_2 **res_dir, int *err)
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{
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struct super_block * sb;
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@ -973,14 +973,13 @@ static struct buffer_head * ext4_dx_find_entry(struct dentry *dentry,
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struct buffer_head *bh;
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ext4_lblk_t block;
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int retval;
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int namelen = dentry->d_name.len;
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const u8 *name = dentry->d_name.name;
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struct inode *dir = dentry->d_parent->d_inode;
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int namelen = d_name->len;
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const u8 *name = d_name->name;
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sb = dir->i_sb;
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/* NFS may look up ".." - look at dx_root directory block */
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if (namelen > 2 || name[0] != '.'||(name[1] != '.' && name[1] != '\0')){
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if (!(frame = dx_probe(dentry, NULL, &hinfo, frames, err)))
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if (!(frame = dx_probe(d_name, dir, &hinfo, frames, err)))
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return NULL;
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} else {
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frame = frames;
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@ -1041,7 +1040,7 @@ static struct dentry *ext4_lookup(struct inode *dir, struct dentry *dentry, stru
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if (dentry->d_name.len > EXT4_NAME_LEN)
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return ERR_PTR(-ENAMETOOLONG);
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bh = ext4_find_entry(dentry, &de);
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bh = ext4_find_entry(dir, &dentry->d_name, &de);
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inode = NULL;
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if (bh) {
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unsigned long ino = le32_to_cpu(de->inode);
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@ -1064,15 +1063,14 @@ struct dentry *ext4_get_parent(struct dentry *child)
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unsigned long ino;
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struct dentry *parent;
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struct inode *inode;
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struct dentry dotdot;
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static const struct qstr dotdot = {
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.name = "..",
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.len = 2,
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};
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struct ext4_dir_entry_2 * de;
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struct buffer_head *bh;
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dotdot.d_name.name = "..";
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dotdot.d_name.len = 2;
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dotdot.d_parent = child; /* confusing, isn't it! */
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bh = ext4_find_entry(&dotdot, &de);
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bh = ext4_find_entry(child->d_inode, &dotdot, &de);
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inode = NULL;
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if (!bh)
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return ERR_PTR(-ENOENT);
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@ -1508,7 +1506,7 @@ static int ext4_dx_add_entry(handle_t *handle, struct dentry *dentry,
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struct ext4_dir_entry_2 *de;
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int err;
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frame = dx_probe(dentry, NULL, &hinfo, frames, &err);
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frame = dx_probe(&dentry->d_name, dir, &hinfo, frames, &err);
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if (!frame)
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return err;
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entries = frame->entries;
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@ -2089,7 +2087,7 @@ static int ext4_rmdir(struct inode *dir, struct dentry *dentry)
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return PTR_ERR(handle);
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retval = -ENOENT;
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bh = ext4_find_entry(dentry, &de);
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bh = ext4_find_entry(dir, &dentry->d_name, &de);
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if (!bh)
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goto end_rmdir;
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@ -2151,7 +2149,7 @@ static int ext4_unlink(struct inode *dir, struct dentry *dentry)
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handle->h_sync = 1;
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retval = -ENOENT;
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bh = ext4_find_entry(dentry, &de);
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bh = ext4_find_entry(dir, &dentry->d_name, &de);
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if (!bh)
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goto end_unlink;
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@ -2312,7 +2310,7 @@ static int ext4_rename(struct inode *old_dir, struct dentry *old_dentry,
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if (IS_DIRSYNC(old_dir) || IS_DIRSYNC(new_dir))
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handle->h_sync = 1;
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old_bh = ext4_find_entry(old_dentry, &old_de);
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old_bh = ext4_find_entry(old_dir, &old_dentry->d_name, &old_de);
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/*
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* Check for inode number is _not_ due to possible IO errors.
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* We might rmdir the source, keep it as pwd of some process
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@ -2325,7 +2323,7 @@ static int ext4_rename(struct inode *old_dir, struct dentry *old_dentry,
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goto end_rename;
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new_inode = new_dentry->d_inode;
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new_bh = ext4_find_entry(new_dentry, &new_de);
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new_bh = ext4_find_entry(new_dir, &new_dentry->d_name, &new_de);
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if (new_bh) {
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if (!new_inode) {
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brelse(new_bh);
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@ -2392,7 +2390,7 @@ static int ext4_rename(struct inode *old_dir, struct dentry *old_dentry,
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struct buffer_head *old_bh2;
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struct ext4_dir_entry_2 *old_de2;
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old_bh2 = ext4_find_entry(old_dentry, &old_de2);
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old_bh2 = ext4_find_entry(old_dir, &old_dentry->d_name, &old_de2);
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if (old_bh2) {
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retval = ext4_delete_entry(handle, old_dir,
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old_de2, old_bh2);
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