From d7dab39b6e16d5eea78ed3c705d2a2d0772b4f06 Mon Sep 17 00:00:00 2001 From: Eric Sandeen Date: Thu, 26 Apr 2012 13:10:39 -0500 Subject: [PATCH] ext3: return 32/64-bit dir name hash according to usage type This is based on commit d1f5273e9adb40724a85272f248f210dc4ce919a ext4: return 32/64-bit dir name hash according to usage type by Fan Yong Traditionally ext2/3/4 has returned a 32-bit hash value from llseek() to appease NFSv2, which can only handle a 32-bit cookie for seekdir() and telldir(). However, this causes problems if there are 32-bit hash collisions, since the NFSv2 server can get stuck resending the same entries from the directory repeatedly. Allow ext3 to return a full 64-bit hash (both major and minor) for telldir to decrease the chance of hash collisions. This patch does implement a new ext3_dir_llseek op, because with 64-bit hashes, nfs will attempt to seek to a hash "offset" which is much larger than ext3's s_maxbytes. So for dx dirs, we call generic_file_llseek_size() with the appropriate max hash value as the maximum seekable size. Otherwise we just pass through to generic_file_llseek(). Patch-updated-by: Bernd Schubert Patch-updated-by: Eric Sandeen (blame us if something is not correct) Signed-off-by: Eric Sandeen Signed-off-by: Jan Kara --- fs/ext3/dir.c | 167 ++++++++++++++++++++++++++++++++++++------------- fs/ext3/ext3.h | 6 +- fs/ext3/hash.c | 4 +- 3 files changed, 129 insertions(+), 48 deletions(-) diff --git a/fs/ext3/dir.c b/fs/ext3/dir.c index cc761ad8fa57..92490e9f85ca 100644 --- a/fs/ext3/dir.c +++ b/fs/ext3/dir.c @@ -21,30 +21,15 @@ * */ +#include #include "ext3.h" static unsigned char ext3_filetype_table[] = { DT_UNKNOWN, DT_REG, DT_DIR, DT_CHR, DT_BLK, DT_FIFO, DT_SOCK, DT_LNK }; -static int ext3_readdir(struct file *, void *, filldir_t); static int ext3_dx_readdir(struct file * filp, void * dirent, filldir_t filldir); -static int ext3_release_dir (struct inode * inode, - struct file * filp); - -const struct file_operations ext3_dir_operations = { - .llseek = generic_file_llseek, - .read = generic_read_dir, - .readdir = ext3_readdir, /* we take BKL. needed?*/ - .unlocked_ioctl = ext3_ioctl, -#ifdef CONFIG_COMPAT - .compat_ioctl = ext3_compat_ioctl, -#endif - .fsync = ext3_sync_file, /* BKL held */ - .release = ext3_release_dir, -}; - static unsigned char get_dtype(struct super_block *sb, int filetype) { @@ -55,6 +40,25 @@ static unsigned char get_dtype(struct super_block *sb, int filetype) return (ext3_filetype_table[filetype]); } +/** + * Check if the given dir-inode refers to an htree-indexed directory + * (or a directory which chould potentially get coverted to use htree + * indexing). + * + * Return 1 if it is a dx dir, 0 if not + */ +static int is_dx_dir(struct inode *inode) +{ + struct super_block *sb = inode->i_sb; + + if (EXT3_HAS_COMPAT_FEATURE(inode->i_sb, + EXT3_FEATURE_COMPAT_DIR_INDEX) && + ((EXT3_I(inode)->i_flags & EXT3_INDEX_FL) || + ((inode->i_size >> sb->s_blocksize_bits) == 1))) + return 1; + + return 0; +} int ext3_check_dir_entry (const char * function, struct inode * dir, struct ext3_dir_entry_2 * de, @@ -94,18 +98,13 @@ static int ext3_readdir(struct file * filp, unsigned long offset; int i, stored; struct ext3_dir_entry_2 *de; - struct super_block *sb; int err; struct inode *inode = filp->f_path.dentry->d_inode; + struct super_block *sb = inode->i_sb; int ret = 0; int dir_has_error = 0; - sb = inode->i_sb; - - if (EXT3_HAS_COMPAT_FEATURE(inode->i_sb, - EXT3_FEATURE_COMPAT_DIR_INDEX) && - ((EXT3_I(inode)->i_flags & EXT3_INDEX_FL) || - ((inode->i_size >> sb->s_blocksize_bits) == 1))) { + if (is_dx_dir(inode)) { err = ext3_dx_readdir(filp, dirent, filldir); if (err != ERR_BAD_DX_DIR) { ret = err; @@ -227,22 +226,87 @@ static int ext3_readdir(struct file * filp, return ret; } +static inline int is_32bit_api(void) +{ +#ifdef CONFIG_COMPAT + return is_compat_task(); +#else + return (BITS_PER_LONG == 32); +#endif +} + /* * These functions convert from the major/minor hash to an f_pos - * value. + * value for dx directories * - * Currently we only use major hash numer. This is unfortunate, but - * on 32-bit machines, the same VFS interface is used for lseek and - * llseek, so if we use the 64 bit offset, then the 32-bit versions of - * lseek/telldir/seekdir will blow out spectacularly, and from within - * the ext2 low-level routine, we don't know if we're being called by - * a 64-bit version of the system call or the 32-bit version of the - * system call. Worse yet, NFSv2 only allows for a 32-bit readdir - * cookie. Sigh. + * Upper layer (for example NFS) should specify FMODE_32BITHASH or + * FMODE_64BITHASH explicitly. On the other hand, we allow ext3 to be mounted + * directly on both 32-bit and 64-bit nodes, under such case, neither + * FMODE_32BITHASH nor FMODE_64BITHASH is specified. */ -#define hash2pos(major, minor) (major >> 1) -#define pos2maj_hash(pos) ((pos << 1) & 0xffffffff) -#define pos2min_hash(pos) (0) +static inline loff_t hash2pos(struct file *filp, __u32 major, __u32 minor) +{ + if ((filp->f_mode & FMODE_32BITHASH) || + (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api())) + return major >> 1; + else + return ((__u64)(major >> 1) << 32) | (__u64)minor; +} + +static inline __u32 pos2maj_hash(struct file *filp, loff_t pos) +{ + if ((filp->f_mode & FMODE_32BITHASH) || + (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api())) + return (pos << 1) & 0xffffffff; + else + return ((pos >> 32) << 1) & 0xffffffff; +} + +static inline __u32 pos2min_hash(struct file *filp, loff_t pos) +{ + if ((filp->f_mode & FMODE_32BITHASH) || + (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api())) + return 0; + else + return pos & 0xffffffff; +} + +/* + * Return 32- or 64-bit end-of-file for dx directories + */ +static inline loff_t ext3_get_htree_eof(struct file *filp) +{ + if ((filp->f_mode & FMODE_32BITHASH) || + (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api())) + return EXT3_HTREE_EOF_32BIT; + else + return EXT3_HTREE_EOF_64BIT; +} + + +/* + * ext3_dir_llseek() calls generic_file_llseek[_size]() to handle both + * non-htree and htree directories, where the "offset" is in terms + * of the filename hash value instead of the byte offset. + * + * Because we may return a 64-bit hash that is well beyond s_maxbytes, + * we need to pass the max hash as the maximum allowable offset in + * the htree directory case. + * + * NOTE: offsets obtained *before* ext3_set_inode_flag(dir, EXT3_INODE_INDEX) + * will be invalid once the directory was converted into a dx directory + */ +loff_t ext3_dir_llseek(struct file *file, loff_t offset, int origin) +{ + struct inode *inode = file->f_mapping->host; + int dx_dir = is_dx_dir(inode); + + if (likely(dx_dir)) + return generic_file_llseek_size(file, offset, origin, + ext3_get_htree_eof(file)); + else + return generic_file_llseek(file, offset, origin); +} /* * This structure holds the nodes of the red-black tree used to store @@ -303,15 +367,16 @@ static void free_rb_tree_fname(struct rb_root *root) } -static struct dir_private_info *ext3_htree_create_dir_info(loff_t pos) +static struct dir_private_info *ext3_htree_create_dir_info(struct file *filp, + loff_t pos) { struct dir_private_info *p; p = kzalloc(sizeof(struct dir_private_info), GFP_KERNEL); if (!p) return NULL; - p->curr_hash = pos2maj_hash(pos); - p->curr_minor_hash = pos2min_hash(pos); + p->curr_hash = pos2maj_hash(filp, pos); + p->curr_minor_hash = pos2min_hash(filp, pos); return p; } @@ -401,7 +466,7 @@ static int call_filldir(struct file * filp, void * dirent, printk("call_filldir: called with null fname?!?\n"); return 0; } - curr_pos = hash2pos(fname->hash, fname->minor_hash); + curr_pos = hash2pos(filp, fname->hash, fname->minor_hash); while (fname) { error = filldir(dirent, fname->name, fname->name_len, curr_pos, @@ -426,13 +491,13 @@ static int ext3_dx_readdir(struct file * filp, int ret; if (!info) { - info = ext3_htree_create_dir_info(filp->f_pos); + info = ext3_htree_create_dir_info(filp, filp->f_pos); if (!info) return -ENOMEM; filp->private_data = info; } - if (filp->f_pos == EXT3_HTREE_EOF) + if (filp->f_pos == ext3_get_htree_eof(filp)) return 0; /* EOF */ /* Some one has messed with f_pos; reset the world */ @@ -440,8 +505,8 @@ static int ext3_dx_readdir(struct file * filp, free_rb_tree_fname(&info->root); info->curr_node = NULL; info->extra_fname = NULL; - info->curr_hash = pos2maj_hash(filp->f_pos); - info->curr_minor_hash = pos2min_hash(filp->f_pos); + info->curr_hash = pos2maj_hash(filp, filp->f_pos); + info->curr_minor_hash = pos2min_hash(filp, filp->f_pos); } /* @@ -473,7 +538,7 @@ static int ext3_dx_readdir(struct file * filp, if (ret < 0) return ret; if (ret == 0) { - filp->f_pos = EXT3_HTREE_EOF; + filp->f_pos = ext3_get_htree_eof(filp); break; } info->curr_node = rb_first(&info->root); @@ -493,7 +558,7 @@ static int ext3_dx_readdir(struct file * filp, info->curr_minor_hash = fname->minor_hash; } else { if (info->next_hash == ~0) { - filp->f_pos = EXT3_HTREE_EOF; + filp->f_pos = ext3_get_htree_eof(filp); break; } info->curr_hash = info->next_hash; @@ -512,3 +577,15 @@ static int ext3_release_dir (struct inode * inode, struct file * filp) return 0; } + +const struct file_operations ext3_dir_operations = { + .llseek = ext3_dir_llseek, + .read = generic_read_dir, + .readdir = ext3_readdir, + .unlocked_ioctl = ext3_ioctl, +#ifdef CONFIG_COMPAT + .compat_ioctl = ext3_compat_ioctl, +#endif + .fsync = ext3_sync_file, + .release = ext3_release_dir, +}; diff --git a/fs/ext3/ext3.h b/fs/ext3/ext3.h index b6515fd7e56c..fe5bef7914ea 100644 --- a/fs/ext3/ext3.h +++ b/fs/ext3/ext3.h @@ -920,7 +920,11 @@ struct dx_hash_info u32 *seed; }; -#define EXT3_HTREE_EOF 0x7fffffff + +/* 32 and 64 bit signed EOF for dx directories */ +#define EXT3_HTREE_EOF_32BIT ((1UL << (32 - 1)) - 1) +#define EXT3_HTREE_EOF_64BIT ((1ULL << (64 - 1)) - 1) + /* * Control parameters used by ext3_htree_next_block diff --git a/fs/ext3/hash.c b/fs/ext3/hash.c index d10231ddcf8a..ede315cdf126 100644 --- a/fs/ext3/hash.c +++ b/fs/ext3/hash.c @@ -198,8 +198,8 @@ int ext3fs_dirhash(const char *name, int len, struct dx_hash_info *hinfo) return -1; } hash = hash & ~1; - if (hash == (EXT3_HTREE_EOF << 1)) - hash = (EXT3_HTREE_EOF-1) << 1; + if (hash == (EXT3_HTREE_EOF_32BIT << 1)) + hash = (EXT3_HTREE_EOF_32BIT - 1) << 1; hinfo->hash = hash; hinfo->minor_hash = minor_hash; return 0; -- GitLab