diff options
Diffstat (limited to 'fs/namei.c')
| -rw-r--r-- | fs/namei.c | 146 |
1 files changed, 141 insertions, 5 deletions
diff --git a/fs/namei.c b/fs/namei.c index 46ea9cc16647..73ec863a9896 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -161,7 +161,7 @@ static char *getname_flags(const char __user *filename, int flags, int *empty) char *getname(const char __user * filename) { - return getname_flags(filename, 0, 0); + return getname_flags(filename, 0, NULL); } #ifdef CONFIG_AUDITSYSCALL @@ -642,7 +642,7 @@ follow_link(struct path *link, struct nameidata *nd, void **p) cond_resched(); current->total_link_count++; - touch_atime(link->mnt, dentry); + touch_atime(link); nd_set_link(nd, NULL); error = security_inode_follow_link(link->dentry, nd); @@ -1374,6 +1374,127 @@ static inline int can_lookup(struct inode *inode) return 1; } +/* + * We can do the critical dentry name comparison and hashing + * operations one word at a time, but we are limited to: + * + * - Architectures with fast unaligned word accesses. We could + * do a "get_unaligned()" if this helps and is sufficiently + * fast. + * + * - Little-endian machines (so that we can generate the mask + * of low bytes efficiently). Again, we *could* do a byte + * swapping load on big-endian architectures if that is not + * expensive enough to make the optimization worthless. + * + * - non-CONFIG_DEBUG_PAGEALLOC configurations (so that we + * do not trap on the (extremely unlikely) case of a page + * crossing operation. + * + * - Furthermore, we need an efficient 64-bit compile for the + * 64-bit case in order to generate the "number of bytes in + * the final mask". Again, that could be replaced with a + * efficient population count instruction or similar. + */ +#ifdef CONFIG_DCACHE_WORD_ACCESS + +#ifdef CONFIG_64BIT + +/* + * Jan Achrenius on G+: microoptimized version of + * the simpler "(mask & ONEBYTES) * ONEBYTES >> 56" + * that works for the bytemasks without having to + * mask them first. + */ +static inline long count_masked_bytes(unsigned long mask) +{ + return mask*0x0001020304050608ul >> 56; +} + +static inline unsigned int fold_hash(unsigned long hash) +{ + hash += hash >> (8*sizeof(int)); + return hash; +} + +#else /* 32-bit case */ + +/* Carl Chatfield / Jan Achrenius G+ version for 32-bit */ +static inline long count_masked_bytes(long mask) +{ + /* (000000 0000ff 00ffff ffffff) -> ( 1 1 2 3 ) */ + long a = (0x0ff0001+mask) >> 23; + /* Fix the 1 for 00 case */ + return a & mask; +} + +#define fold_hash(x) (x) + +#endif + +unsigned int full_name_hash(const unsigned char *name, unsigned int len) +{ + unsigned long a, mask; + unsigned long hash = 0; + + for (;;) { + a = *(unsigned long *)name; + if (len < sizeof(unsigned long)) + break; + hash += a; + hash *= 9; + name += sizeof(unsigned long); + len -= sizeof(unsigned long); + if (!len) + goto done; + } + mask = ~(~0ul << len*8); + hash += mask & a; +done: + return fold_hash(hash); +} +EXPORT_SYMBOL(full_name_hash); + +#define REPEAT_BYTE(x) ((~0ul / 0xff) * (x)) +#define ONEBYTES REPEAT_BYTE(0x01) +#define SLASHBYTES REPEAT_BYTE('/') +#define HIGHBITS REPEAT_BYTE(0x80) + +/* Return the high bit set in the first byte that is a zero */ +static inline unsigned long has_zero(unsigned long a) +{ + return ((a - ONEBYTES) & ~a) & HIGHBITS; +} + +/* + * Calculate the length and hash of the path component, and + * return the length of the component; + */ +static inline unsigned long hash_name(const char *name, unsigned int *hashp) +{ + unsigned long a, mask, hash, len; + + hash = a = 0; + len = -sizeof(unsigned long); + do { + hash = (hash + a) * 9; + len += sizeof(unsigned long); + a = *(unsigned long *)(name+len); + /* Do we have any NUL or '/' bytes in this word? */ + mask = has_zero(a) | has_zero(a ^ SLASHBYTES); + } while (!mask); + + /* The mask *below* the first high bit set */ + mask = (mask - 1) & ~mask; + mask >>= 7; + hash += a & mask; + *hashp = fold_hash(hash); + + return len + count_masked_bytes(mask); +} + +#else + unsigned int full_name_hash(const unsigned char *name, unsigned int len) { unsigned long hash = init_name_hash(); @@ -1402,6 +1523,8 @@ static inline unsigned long hash_name(const char *name, unsigned int *hashp) return len; } +#endif + /* * Name resolution. * This is the basic name resolution function, turning a pathname into @@ -1849,7 +1972,7 @@ int user_path_at_empty(int dfd, const char __user *name, unsigned flags, int user_path_at(int dfd, const char __user *name, unsigned flags, struct path *path) { - return user_path_at_empty(dfd, name, flags, path, 0); + return user_path_at_empty(dfd, name, flags, path, NULL); } static int user_path_parent(int dfd, const char __user *path, @@ -2569,6 +2692,7 @@ SYSCALL_DEFINE3(mknod, const char __user *, filename, umode_t, mode, unsigned, d int vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) { int error = may_create(dir, dentry); + unsigned max_links = dir->i_sb->s_max_links; if (error) return error; @@ -2581,6 +2705,9 @@ int vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) if (error) return error; + if (max_links && dir->i_nlink >= max_links) + return -EMLINK; + error = dir->i_op->mkdir(dir, dentry, mode); if (!error) fsnotify_mkdir(dir, dentry); @@ -2911,6 +3038,7 @@ SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newn int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry) { struct inode *inode = old_dentry->d_inode; + unsigned max_links = dir->i_sb->s_max_links; int error; if (!inode) @@ -2941,6 +3069,8 @@ int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_de /* Make sure we don't allow creating hardlink to an unlinked file */ if (inode->i_nlink == 0) error = -ENOENT; + else if (max_links && inode->i_nlink >= max_links) + error = -EMLINK; else error = dir->i_op->link(old_dentry, dir, new_dentry); mutex_unlock(&inode->i_mutex); @@ -3050,6 +3180,7 @@ static int vfs_rename_dir(struct inode *old_dir, struct dentry *old_dentry, { int error = 0; struct inode *target = new_dentry->d_inode; + unsigned max_links = new_dir->i_sb->s_max_links; /* * If we are going to change the parent - check write permissions, @@ -3073,6 +3204,11 @@ static int vfs_rename_dir(struct inode *old_dir, struct dentry *old_dentry, if (d_mountpoint(old_dentry) || d_mountpoint(new_dentry)) goto out; + error = -EMLINK; + if (max_links && !target && new_dir != old_dir && + new_dir->i_nlink >= max_links) + goto out; + if (target) shrink_dcache_parent(new_dentry); error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); @@ -3371,9 +3507,9 @@ retry: if (err) goto fail; - kaddr = kmap_atomic(page, KM_USER0); + kaddr = kmap_atomic(page); memcpy(kaddr, symname, len-1); - kunmap_atomic(kaddr, KM_USER0); + kunmap_atomic(kaddr); err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, page, fsdata); |