From cad3f00763dcf9dfc62cbddf4bd714ab5a71a0eb Mon Sep 17 00:00:00 2001 From: Theodore Ts'o Date: Sun, 19 Dec 2010 22:07:02 -0500 Subject: [PATCH] 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" --- fs/ext4/dir.c | 40 +++++++++++++++++++++++----------------- fs/ext4/ext4.h | 3 ++- fs/ext4/namei.c | 14 +++++++------- 3 files changed, 32 insertions(+), 25 deletions(-) diff --git a/fs/ext4/dir.c b/fs/ext4/dir.c index ece76fb..bd5d74d 100644 --- a/fs/ext4/dir.c +++ b/fs/ext4/dir.c @@ -60,7 +60,11 @@ static unsigned char get_dtype(struct super_block *sb, int filetype) return (ext4_filetype_table[filetype]); } - +/* + * Return 0 if the directory entry is OK, and 1 if there is a problem + * + * Note: this is the opposite of what ext2 and ext3 historically returned... + */ int __ext4_check_dir_entry(const char *function, unsigned int line, struct inode *dir, struct ext4_dir_entry_2 *de, @@ -71,26 +75,28 @@ int __ext4_check_dir_entry(const char *function, unsigned int line, const int rlen = ext4_rec_len_from_disk(de->rec_len, dir->i_sb->s_blocksize); - if (rlen < EXT4_DIR_REC_LEN(1)) + if (unlikely(rlen < EXT4_DIR_REC_LEN(1))) error_msg = "rec_len is smaller than minimal"; - else if (rlen % 4 != 0) + else if (unlikely(rlen % 4 != 0)) error_msg = "rec_len % 4 != 0"; - else if (rlen < EXT4_DIR_REC_LEN(de->name_len)) + else if (unlikely(rlen < EXT4_DIR_REC_LEN(de->name_len))) error_msg = "rec_len is too small for name_len"; - else if (((char *) de - bh->b_data) + rlen > dir->i_sb->s_blocksize) + else if (unlikely(((char *) de - bh->b_data) + rlen > + dir->i_sb->s_blocksize)) error_msg = "directory entry across blocks"; - else if (le32_to_cpu(de->inode) > - le32_to_cpu(EXT4_SB(dir->i_sb)->s_es->s_inodes_count)) + else if (unlikely(le32_to_cpu(de->inode) > + le32_to_cpu(EXT4_SB(dir->i_sb)->s_es->s_inodes_count))) error_msg = "inode out of bounds"; + else + return 0; - if (error_msg != NULL) - ext4_error_inode(dir, function, line, bh->b_blocknr, - "bad entry in directory: %s - " - "offset=%u(%u), inode=%u, rec_len=%d, name_len=%d", - error_msg, (unsigned) (offset%bh->b_size), offset, - le32_to_cpu(de->inode), - rlen, de->name_len); - return error_msg == NULL ? 1 : 0; + ext4_error_inode(dir, function, line, bh->b_blocknr, + "bad entry in directory: %s - " + "offset=%u(%u), inode=%u, rec_len=%d, name_len=%d", + error_msg, (unsigned) (offset%bh->b_size), offset, + le32_to_cpu(de->inode), + rlen, de->name_len); + return 1; } static int ext4_readdir(struct file *filp, @@ -194,8 +200,8 @@ revalidate: while (!error && filp->f_pos < inode->i_size && offset < sb->s_blocksize) { de = (struct ext4_dir_entry_2 *) (bh->b_data + offset); - if (!ext4_check_dir_entry(inode, de, - bh, offset)) { + if (ext4_check_dir_entry(inode, de, + bh, offset)) { /* * On error, skip the f_pos to the next block */ diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h index 17baecb..49f1cea 100644 --- a/fs/ext4/ext4.h +++ b/fs/ext4/ext4.h @@ -1639,7 +1639,8 @@ extern int __ext4_check_dir_entry(const char *, unsigned int, struct inode *, struct ext4_dir_entry_2 *, struct buffer_head *, unsigned int); #define ext4_check_dir_entry(dir, de, bh, offset) \ - __ext4_check_dir_entry(__func__, __LINE__, (dir), (de), (bh), (offset)) + unlikely(__ext4_check_dir_entry(__func__, __LINE__, (dir), (de), \ + (bh), (offset))) extern int ext4_htree_store_dirent(struct file *dir_file, __u32 hash, __u32 minor_hash, struct ext4_dir_entry_2 *dirent); diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c index 2030864..e275464 100644 --- a/fs/ext4/namei.c +++ b/fs/ext4/namei.c @@ -581,9 +581,9 @@ static int htree_dirblock_to_tree(struct file *dir_file, dir->i_sb->s_blocksize - EXT4_DIR_REC_LEN(0)); for (; de < top; de = ext4_next_entry(de, dir->i_sb->s_blocksize)) { - if (!ext4_check_dir_entry(dir, de, bh, - (block<i_sb)) - +((char *)de - bh->b_data))) { + if (ext4_check_dir_entry(dir, de, bh, + (block<i_sb)) + + ((char *)de - bh->b_data))) { /* On error, skip the f_pos to the next block. */ dir_file->f_pos = (dir_file->f_pos | (dir->i_sb->s_blocksize - 1)) + 1; @@ -820,7 +820,7 @@ static inline int search_dirblock(struct buffer_head *bh, if ((char *) de + namelen <= dlimit && ext4_match (namelen, name, de)) { /* found a match - just to be sure, do a full check */ - if (!ext4_check_dir_entry(dir, de, bh, offset)) + if (ext4_check_dir_entry(dir, de, bh, offset)) return -1; *res_dir = de; return 1; @@ -1269,7 +1269,7 @@ static int add_dirent_to_buf(handle_t *handle, struct dentry *dentry, de = (struct ext4_dir_entry_2 *)bh->b_data; top = bh->b_data + blocksize - reclen; while ((char *) de <= top) { - if (!ext4_check_dir_entry(dir, de, bh, offset)) + if (ext4_check_dir_entry(dir, de, bh, offset)) return -EIO; if (ext4_match(namelen, name, de)) return -EEXIST; @@ -1636,7 +1636,7 @@ static int ext4_delete_entry(handle_t *handle, pde = NULL; de = (struct ext4_dir_entry_2 *) bh->b_data; while (i < bh->b_size) { - if (!ext4_check_dir_entry(dir, de, bh, i)) + if (ext4_check_dir_entry(dir, de, bh, i)) return -EIO; if (de == de_del) { BUFFER_TRACE(bh, "get_write_access"); @@ -1919,7 +1919,7 @@ static int empty_dir(struct inode *inode) } de = (struct ext4_dir_entry_2 *) bh->b_data; } - if (!ext4_check_dir_entry(inode, de, bh, offset)) { + if (ext4_check_dir_entry(inode, de, bh, offset)) { de = (struct ext4_dir_entry_2 *)(bh->b_data + sb->s_blocksize); offset = (offset | (sb->s_blocksize - 1)) + 1; -- 2.7.4