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ext4: optimize ext4_check_dir_entry() with unlikely() annotations
This function gets called a lot for large directories, and the answer is almost always "no, no, there's no problem". This means using unlikely() is a good thing. Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
This commit is contained in:
parent
b17b35ec13
commit
cad3f00763
3 changed files with 32 additions and 25 deletions
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@ -60,7 +60,11 @@ static unsigned char get_dtype(struct super_block *sb, int filetype)
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return (ext4_filetype_table[filetype]);
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}
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/*
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* Return 0 if the directory entry is OK, and 1 if there is a problem
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*
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* Note: this is the opposite of what ext2 and ext3 historically returned...
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*/
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int __ext4_check_dir_entry(const char *function, unsigned int line,
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struct inode *dir,
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struct ext4_dir_entry_2 *de,
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@ -71,26 +75,28 @@ int __ext4_check_dir_entry(const char *function, unsigned int line,
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const int rlen = ext4_rec_len_from_disk(de->rec_len,
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dir->i_sb->s_blocksize);
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if (rlen < EXT4_DIR_REC_LEN(1))
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if (unlikely(rlen < EXT4_DIR_REC_LEN(1)))
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error_msg = "rec_len is smaller than minimal";
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else if (rlen % 4 != 0)
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else if (unlikely(rlen % 4 != 0))
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error_msg = "rec_len % 4 != 0";
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else if (rlen < EXT4_DIR_REC_LEN(de->name_len))
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else if (unlikely(rlen < EXT4_DIR_REC_LEN(de->name_len)))
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error_msg = "rec_len is too small for name_len";
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else if (((char *) de - bh->b_data) + rlen > dir->i_sb->s_blocksize)
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else if (unlikely(((char *) de - bh->b_data) + rlen >
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dir->i_sb->s_blocksize))
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error_msg = "directory entry across blocks";
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else if (le32_to_cpu(de->inode) >
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le32_to_cpu(EXT4_SB(dir->i_sb)->s_es->s_inodes_count))
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else if (unlikely(le32_to_cpu(de->inode) >
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le32_to_cpu(EXT4_SB(dir->i_sb)->s_es->s_inodes_count)))
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error_msg = "inode out of bounds";
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else
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return 0;
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if (error_msg != NULL)
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ext4_error_inode(dir, function, line, bh->b_blocknr,
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"bad entry in directory: %s - "
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"offset=%u(%u), inode=%u, rec_len=%d, name_len=%d",
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error_msg, (unsigned) (offset%bh->b_size), offset,
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le32_to_cpu(de->inode),
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rlen, de->name_len);
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return error_msg == NULL ? 1 : 0;
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ext4_error_inode(dir, function, line, bh->b_blocknr,
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"bad entry in directory: %s - "
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"offset=%u(%u), inode=%u, rec_len=%d, name_len=%d",
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error_msg, (unsigned) (offset%bh->b_size), offset,
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le32_to_cpu(de->inode),
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rlen, de->name_len);
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return 1;
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}
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static int ext4_readdir(struct file *filp,
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@ -194,8 +200,8 @@ static int ext4_readdir(struct file *filp,
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while (!error && filp->f_pos < inode->i_size
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&& offset < sb->s_blocksize) {
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de = (struct ext4_dir_entry_2 *) (bh->b_data + offset);
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if (!ext4_check_dir_entry(inode, de,
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bh, offset)) {
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if (ext4_check_dir_entry(inode, de,
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bh, offset)) {
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/*
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* On error, skip the f_pos to the next block
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*/
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@ -1639,7 +1639,8 @@ extern int __ext4_check_dir_entry(const char *, unsigned int, struct inode *,
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struct ext4_dir_entry_2 *,
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struct buffer_head *, unsigned int);
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#define ext4_check_dir_entry(dir, de, bh, offset) \
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__ext4_check_dir_entry(__func__, __LINE__, (dir), (de), (bh), (offset))
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unlikely(__ext4_check_dir_entry(__func__, __LINE__, (dir), (de), \
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(bh), (offset)))
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extern int ext4_htree_store_dirent(struct file *dir_file, __u32 hash,
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__u32 minor_hash,
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struct ext4_dir_entry_2 *dirent);
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@ -581,9 +581,9 @@ static int htree_dirblock_to_tree(struct file *dir_file,
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dir->i_sb->s_blocksize -
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EXT4_DIR_REC_LEN(0));
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for (; de < top; de = ext4_next_entry(de, dir->i_sb->s_blocksize)) {
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if (!ext4_check_dir_entry(dir, de, bh,
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(block<<EXT4_BLOCK_SIZE_BITS(dir->i_sb))
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+((char *)de - bh->b_data))) {
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if (ext4_check_dir_entry(dir, de, bh,
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(block<<EXT4_BLOCK_SIZE_BITS(dir->i_sb))
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+ ((char *)de - bh->b_data))) {
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/* On error, skip the f_pos to the next block. */
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dir_file->f_pos = (dir_file->f_pos |
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(dir->i_sb->s_blocksize - 1)) + 1;
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@ -820,7 +820,7 @@ static inline int search_dirblock(struct buffer_head *bh,
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if ((char *) de + namelen <= dlimit &&
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ext4_match (namelen, name, de)) {
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/* found a match - just to be sure, do a full check */
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if (!ext4_check_dir_entry(dir, de, bh, offset))
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if (ext4_check_dir_entry(dir, de, bh, offset))
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return -1;
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*res_dir = de;
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return 1;
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@ -1269,7 +1269,7 @@ static int add_dirent_to_buf(handle_t *handle, struct dentry *dentry,
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de = (struct ext4_dir_entry_2 *)bh->b_data;
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top = bh->b_data + blocksize - reclen;
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while ((char *) de <= top) {
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if (!ext4_check_dir_entry(dir, de, bh, offset))
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if (ext4_check_dir_entry(dir, de, bh, offset))
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return -EIO;
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if (ext4_match(namelen, name, de))
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return -EEXIST;
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@ -1636,7 +1636,7 @@ static int ext4_delete_entry(handle_t *handle,
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pde = NULL;
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de = (struct ext4_dir_entry_2 *) bh->b_data;
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while (i < bh->b_size) {
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if (!ext4_check_dir_entry(dir, de, bh, i))
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if (ext4_check_dir_entry(dir, de, bh, i))
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return -EIO;
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if (de == de_del) {
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BUFFER_TRACE(bh, "get_write_access");
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@ -1919,7 +1919,7 @@ static int empty_dir(struct inode *inode)
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}
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de = (struct ext4_dir_entry_2 *) bh->b_data;
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}
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if (!ext4_check_dir_entry(inode, de, bh, offset)) {
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if (ext4_check_dir_entry(inode, de, bh, offset)) {
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de = (struct ext4_dir_entry_2 *)(bh->b_data +
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sb->s_blocksize);
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offset = (offset | (sb->s_blocksize - 1)) + 1;
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