ext3: return 32/64-bit dir name hash according to usage type
This is based on commit d1f5273e9a
ext4: return 32/64-bit dir name hash according to usage type
by Fan Yong <yong.fan@whamcloud.com>
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 <bernd.schubert@itwm.fraunhofer.de>
Patch-updated-by: Eric Sandeen <sandeen@redhat.com>
(blame us if something is not correct)
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: Jan Kara <jack@suse.cz>
This commit is contained in:
Eric Sandeen
Jan Kara
parent
a80b12c3d0
commit
d7dab39b6e
167
fs/ext3/dir.c
167
fs/ext3/dir.c
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@ -21,30 +21,15 @@
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*
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*/
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#include <linux/compat.h>
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#include "ext3.h"
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static unsigned char ext3_filetype_table[] = {
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DT_UNKNOWN, DT_REG, DT_DIR, DT_CHR, DT_BLK, DT_FIFO, DT_SOCK, DT_LNK
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};
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static int ext3_readdir(struct file *, void *, filldir_t);
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static int ext3_dx_readdir(struct file * filp,
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void * dirent, filldir_t filldir);
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static int ext3_release_dir (struct inode * inode,
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struct file * filp);
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const struct file_operations ext3_dir_operations = {
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.llseek = generic_file_llseek,
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.read = generic_read_dir,
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.readdir = ext3_readdir, /* we take BKL. needed?*/
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.unlocked_ioctl = ext3_ioctl,
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#ifdef CONFIG_COMPAT
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.compat_ioctl = ext3_compat_ioctl,
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#endif
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.fsync = ext3_sync_file, /* BKL held */
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.release = ext3_release_dir,
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};
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static unsigned char get_dtype(struct super_block *sb, int filetype)
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{
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@ -55,6 +40,25 @@ static unsigned char get_dtype(struct super_block *sb, int filetype)
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return (ext3_filetype_table[filetype]);
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}
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/**
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* Check if the given dir-inode refers to an htree-indexed directory
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* (or a directory which chould potentially get coverted to use htree
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* indexing).
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*
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* Return 1 if it is a dx dir, 0 if not
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*/
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static int is_dx_dir(struct inode *inode)
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{
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struct super_block *sb = inode->i_sb;
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if (EXT3_HAS_COMPAT_FEATURE(inode->i_sb,
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EXT3_FEATURE_COMPAT_DIR_INDEX) &&
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((EXT3_I(inode)->i_flags & EXT3_INDEX_FL) ||
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((inode->i_size >> sb->s_blocksize_bits) == 1)))
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return 1;
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return 0;
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}
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int ext3_check_dir_entry (const char * function, struct inode * dir,
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struct ext3_dir_entry_2 * de,
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@ -94,18 +98,13 @@ static int ext3_readdir(struct file * filp,
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unsigned long offset;
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int i, stored;
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struct ext3_dir_entry_2 *de;
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struct super_block *sb;
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int err;
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struct inode *inode = filp->f_path.dentry->d_inode;
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struct super_block *sb = inode->i_sb;
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int ret = 0;
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int dir_has_error = 0;
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sb = inode->i_sb;
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if (EXT3_HAS_COMPAT_FEATURE(inode->i_sb,
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EXT3_FEATURE_COMPAT_DIR_INDEX) &&
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((EXT3_I(inode)->i_flags & EXT3_INDEX_FL) ||
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((inode->i_size >> sb->s_blocksize_bits) == 1))) {
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if (is_dx_dir(inode)) {
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err = ext3_dx_readdir(filp, dirent, filldir);
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if (err != ERR_BAD_DX_DIR) {
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ret = err;
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@ -227,22 +226,87 @@ out:
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return ret;
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}
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static inline int is_32bit_api(void)
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{
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#ifdef CONFIG_COMPAT
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return is_compat_task();
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#else
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return (BITS_PER_LONG == 32);
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#endif
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}
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/*
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* These functions convert from the major/minor hash to an f_pos
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* value.
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* value for dx directories
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*
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* Currently we only use major hash numer. This is unfortunate, but
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* on 32-bit machines, the same VFS interface is used for lseek and
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* llseek, so if we use the 64 bit offset, then the 32-bit versions of
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* lseek/telldir/seekdir will blow out spectacularly, and from within
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* the ext2 low-level routine, we don't know if we're being called by
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* a 64-bit version of the system call or the 32-bit version of the
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* system call. Worse yet, NFSv2 only allows for a 32-bit readdir
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* cookie. Sigh.
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* Upper layer (for example NFS) should specify FMODE_32BITHASH or
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* FMODE_64BITHASH explicitly. On the other hand, we allow ext3 to be mounted
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* directly on both 32-bit and 64-bit nodes, under such case, neither
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* FMODE_32BITHASH nor FMODE_64BITHASH is specified.
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*/
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#define hash2pos(major, minor) (major >> 1)
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#define pos2maj_hash(pos) ((pos << 1) & 0xffffffff)
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#define pos2min_hash(pos) (0)
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static inline loff_t hash2pos(struct file *filp, __u32 major, __u32 minor)
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{
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if ((filp->f_mode & FMODE_32BITHASH) ||
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(!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api()))
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return major >> 1;
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else
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return ((__u64)(major >> 1) << 32) | (__u64)minor;
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}
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static inline __u32 pos2maj_hash(struct file *filp, loff_t pos)
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{
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if ((filp->f_mode & FMODE_32BITHASH) ||
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(!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api()))
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return (pos << 1) & 0xffffffff;
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else
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return ((pos >> 32) << 1) & 0xffffffff;
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}
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static inline __u32 pos2min_hash(struct file *filp, loff_t pos)
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{
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if ((filp->f_mode & FMODE_32BITHASH) ||
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(!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api()))
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return 0;
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else
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return pos & 0xffffffff;
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}
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/*
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* Return 32- or 64-bit end-of-file for dx directories
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*/
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static inline loff_t ext3_get_htree_eof(struct file *filp)
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{
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if ((filp->f_mode & FMODE_32BITHASH) ||
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(!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api()))
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return EXT3_HTREE_EOF_32BIT;
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else
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return EXT3_HTREE_EOF_64BIT;
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}
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/*
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* ext3_dir_llseek() calls generic_file_llseek[_size]() to handle both
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* non-htree and htree directories, where the "offset" is in terms
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* of the filename hash value instead of the byte offset.
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*
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* Because we may return a 64-bit hash that is well beyond s_maxbytes,
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* we need to pass the max hash as the maximum allowable offset in
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* the htree directory case.
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*
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* NOTE: offsets obtained *before* ext3_set_inode_flag(dir, EXT3_INODE_INDEX)
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* will be invalid once the directory was converted into a dx directory
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*/
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loff_t ext3_dir_llseek(struct file *file, loff_t offset, int origin)
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{
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struct inode *inode = file->f_mapping->host;
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int dx_dir = is_dx_dir(inode);
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if (likely(dx_dir))
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return generic_file_llseek_size(file, offset, origin,
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ext3_get_htree_eof(file));
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else
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return generic_file_llseek(file, offset, origin);
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}
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/*
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* This structure holds the nodes of the red-black tree used to store
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@ -303,15 +367,16 @@ static void free_rb_tree_fname(struct rb_root *root)
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}
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static struct dir_private_info *ext3_htree_create_dir_info(loff_t pos)
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static struct dir_private_info *ext3_htree_create_dir_info(struct file *filp,
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loff_t pos)
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{
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struct dir_private_info *p;
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p = kzalloc(sizeof(struct dir_private_info), GFP_KERNEL);
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if (!p)
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return NULL;
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p->curr_hash = pos2maj_hash(pos);
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p->curr_minor_hash = pos2min_hash(pos);
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p->curr_hash = pos2maj_hash(filp, pos);
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p->curr_minor_hash = pos2min_hash(filp, pos);
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return p;
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}
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@ -401,7 +466,7 @@ static int call_filldir(struct file * filp, void * dirent,
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printk("call_filldir: called with null fname?!?\n");
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return 0;
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}
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curr_pos = hash2pos(fname->hash, fname->minor_hash);
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curr_pos = hash2pos(filp, fname->hash, fname->minor_hash);
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while (fname) {
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error = filldir(dirent, fname->name,
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fname->name_len, curr_pos,
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@ -426,13 +491,13 @@ static int ext3_dx_readdir(struct file * filp,
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int ret;
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if (!info) {
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info = ext3_htree_create_dir_info(filp->f_pos);
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info = ext3_htree_create_dir_info(filp, filp->f_pos);
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if (!info)
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return -ENOMEM;
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filp->private_data = info;
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}
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if (filp->f_pos == EXT3_HTREE_EOF)
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if (filp->f_pos == ext3_get_htree_eof(filp))
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return 0; /* EOF */
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/* Some one has messed with f_pos; reset the world */
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@ -440,8 +505,8 @@ static int ext3_dx_readdir(struct file * filp,
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free_rb_tree_fname(&info->root);
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info->curr_node = NULL;
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info->extra_fname = NULL;
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info->curr_hash = pos2maj_hash(filp->f_pos);
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info->curr_minor_hash = pos2min_hash(filp->f_pos);
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info->curr_hash = pos2maj_hash(filp, filp->f_pos);
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info->curr_minor_hash = pos2min_hash(filp, filp->f_pos);
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}
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/*
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@ -473,7 +538,7 @@ static int ext3_dx_readdir(struct file * filp,
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if (ret < 0)
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return ret;
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if (ret == 0) {
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filp->f_pos = EXT3_HTREE_EOF;
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filp->f_pos = ext3_get_htree_eof(filp);
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break;
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}
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info->curr_node = rb_first(&info->root);
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@ -493,7 +558,7 @@ static int ext3_dx_readdir(struct file * filp,
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info->curr_minor_hash = fname->minor_hash;
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} else {
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if (info->next_hash == ~0) {
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filp->f_pos = EXT3_HTREE_EOF;
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filp->f_pos = ext3_get_htree_eof(filp);
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break;
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}
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info->curr_hash = info->next_hash;
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@ -512,3 +577,15 @@ static int ext3_release_dir (struct inode * inode, struct file * filp)
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return 0;
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}
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const struct file_operations ext3_dir_operations = {
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.llseek = ext3_dir_llseek,
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.read = generic_read_dir,
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.readdir = ext3_readdir,
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.unlocked_ioctl = ext3_ioctl,
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#ifdef CONFIG_COMPAT
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.compat_ioctl = ext3_compat_ioctl,
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#endif
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.fsync = ext3_sync_file,
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.release = ext3_release_dir,
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};
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@ -920,7 +920,11 @@ struct dx_hash_info
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u32 *seed;
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};
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#define EXT3_HTREE_EOF 0x7fffffff
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/* 32 and 64 bit signed EOF for dx directories */
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#define EXT3_HTREE_EOF_32BIT ((1UL << (32 - 1)) - 1)
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#define EXT3_HTREE_EOF_64BIT ((1ULL << (64 - 1)) - 1)
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/*
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* Control parameters used by ext3_htree_next_block
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@ -198,8 +198,8 @@ int ext3fs_dirhash(const char *name, int len, struct dx_hash_info *hinfo)
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return -1;
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}
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hash = hash & ~1;
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if (hash == (EXT3_HTREE_EOF << 1))
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hash = (EXT3_HTREE_EOF-1) << 1;
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if (hash == (EXT3_HTREE_EOF_32BIT << 1))
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hash = (EXT3_HTREE_EOF_32BIT - 1) << 1;
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hinfo->hash = hash;
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hinfo->minor_hash = minor_hash;
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return 0;
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