diff options
Diffstat (limited to 'fs/namei.c')
-rw-r--r-- | fs/namei.c | 96 |
1 files changed, 53 insertions, 43 deletions
@@ -34,6 +34,7 @@ #include <linux/device_cgroup.h> #include <linux/fs_struct.h> #include <linux/posix_acl.h> +#include <linux/hash.h> #include <asm/uaccess.h> #include "internal.h" @@ -643,24 +644,22 @@ static int complete_walk(struct nameidata *nd) static __always_inline void set_root(struct nameidata *nd) { - if (!nd->root.mnt) - get_fs_root(current->fs, &nd->root); + get_fs_root(current->fs, &nd->root); } static int link_path_walk(const char *, struct nameidata *); -static __always_inline void set_root_rcu(struct nameidata *nd) +static __always_inline unsigned set_root_rcu(struct nameidata *nd) { - if (!nd->root.mnt) { - struct fs_struct *fs = current->fs; - unsigned seq; + struct fs_struct *fs = current->fs; + unsigned seq, res; - do { - seq = read_seqcount_begin(&fs->seq); - nd->root = fs->root; - nd->seq = __read_seqcount_begin(&nd->root.dentry->d_seq); - } while (read_seqcount_retry(&fs->seq, seq)); - } + do { + seq = read_seqcount_begin(&fs->seq); + nd->root = fs->root; + res = __read_seqcount_begin(&nd->root.dentry->d_seq); + } while (read_seqcount_retry(&fs->seq, seq)); + return res; } static void path_put_conditional(struct path *path, struct nameidata *nd) @@ -860,7 +859,8 @@ follow_link(struct path *link, struct nameidata *nd, void **p) return PTR_ERR(s); } if (*s == '/') { - set_root(nd); + if (!nd->root.mnt) + set_root(nd); path_put(&nd->path); nd->path = nd->root; path_get(&nd->root); @@ -1137,13 +1137,15 @@ static bool __follow_mount_rcu(struct nameidata *nd, struct path *path, */ *inode = path->dentry->d_inode; } - return read_seqretry(&mount_lock, nd->m_seq) && + return !read_seqretry(&mount_lock, nd->m_seq) && !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT); } static int follow_dotdot_rcu(struct nameidata *nd) { - set_root_rcu(nd); + struct inode *inode = nd->inode; + if (!nd->root.mnt) + set_root_rcu(nd); while (1) { if (nd->path.dentry == nd->root.dentry && @@ -1155,6 +1157,7 @@ static int follow_dotdot_rcu(struct nameidata *nd) struct dentry *parent = old->d_parent; unsigned seq; + inode = parent->d_inode; seq = read_seqcount_begin(&parent->d_seq); if (read_seqcount_retry(&old->d_seq, nd->seq)) goto failed; @@ -1164,6 +1167,7 @@ static int follow_dotdot_rcu(struct nameidata *nd) } if (!follow_up_rcu(&nd->path)) break; + inode = nd->path.dentry->d_inode; nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); } while (d_mountpoint(nd->path.dentry)) { @@ -1173,11 +1177,12 @@ static int follow_dotdot_rcu(struct nameidata *nd) break; nd->path.mnt = &mounted->mnt; nd->path.dentry = mounted->mnt.mnt_root; + inode = nd->path.dentry->d_inode; nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); - if (!read_seqretry(&mount_lock, nd->m_seq)) + if (read_seqretry(&mount_lock, nd->m_seq)) goto failed; } - nd->inode = nd->path.dentry->d_inode; + nd->inode = inode; return 0; failed: @@ -1256,7 +1261,8 @@ static void follow_mount(struct path *path) static void follow_dotdot(struct nameidata *nd) { - set_root(nd); + if (!nd->root.mnt) + set_root(nd); while(1) { struct dentry *old = nd->path.dentry; @@ -1634,8 +1640,7 @@ static inline int nested_symlink(struct path *path, struct nameidata *nd) static inline unsigned int fold_hash(unsigned long hash) { - hash += hash >> (8*sizeof(int)); - return hash; + return hash_64(hash, 32); } #else /* 32-bit case */ @@ -1669,9 +1674,9 @@ EXPORT_SYMBOL(full_name_hash); /* * Calculate the length and hash of the path component, and - * return the length of the component; + * return the "hash_len" as the result. */ -static inline unsigned long hash_name(const char *name, unsigned int *hashp) +static inline u64 hash_name(const char *name) { unsigned long a, b, adata, bdata, mask, hash, len; const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; @@ -1691,9 +1696,8 @@ static inline unsigned long hash_name(const char *name, unsigned int *hashp) mask = create_zero_mask(adata | bdata); hash += a & zero_bytemask(mask); - *hashp = fold_hash(hash); - - return len + find_zero(mask); + len += find_zero(mask); + return hashlen_create(fold_hash(hash), len); } #else @@ -1711,7 +1715,7 @@ EXPORT_SYMBOL(full_name_hash); * We know there's a real path component here of at least * one character. */ -static inline unsigned long hash_name(const char *name, unsigned int *hashp) +static inline u64 hash_name(const char *name) { unsigned long hash = init_name_hash(); unsigned long len = 0, c; @@ -1722,8 +1726,7 @@ static inline unsigned long hash_name(const char *name, unsigned int *hashp) hash = partial_name_hash(c, hash); c = (unsigned char)name[len]; } while (c && c != '/'); - *hashp = end_name_hash(hash); - return len; + return hashlen_create(end_name_hash(hash), len); } #endif @@ -1748,20 +1751,17 @@ static int link_path_walk(const char *name, struct nameidata *nd) /* At this point we know we have a real path component. */ for(;;) { - struct qstr this; - long len; + u64 hash_len; int type; err = may_lookup(nd); if (err) break; - len = hash_name(name, &this.hash); - this.name = name; - this.len = len; + hash_len = hash_name(name); type = LAST_NORM; - if (name[0] == '.') switch (len) { + if (name[0] == '.') switch (hashlen_len(hash_len)) { case 2: if (name[1] == '.') { type = LAST_DOTDOT; @@ -1775,29 +1775,32 @@ static int link_path_walk(const char *name, struct nameidata *nd) struct dentry *parent = nd->path.dentry; nd->flags &= ~LOOKUP_JUMPED; if (unlikely(parent->d_flags & DCACHE_OP_HASH)) { + struct qstr this = { { .hash_len = hash_len }, .name = name }; err = parent->d_op->d_hash(parent, &this); if (err < 0) break; + hash_len = this.hash_len; + name = this.name; } } - nd->last = this; + nd->last.hash_len = hash_len; + nd->last.name = name; nd->last_type = type; - if (!name[len]) + name += hashlen_len(hash_len); + if (!*name) return 0; /* * If it wasn't NUL, we know it was '/'. Skip that * slash, and continue until no more slashes. */ do { - len++; - } while (unlikely(name[len] == '/')); - if (!name[len]) + name++; + } while (unlikely(*name == '/')); + if (!*name) return 0; - name += len; - err = walk_component(nd, &next, LOOKUP_FOLLOW); if (err < 0) return err; @@ -1852,7 +1855,7 @@ static int path_init(int dfd, const char *name, unsigned int flags, if (*name=='/') { if (flags & LOOKUP_RCU) { rcu_read_lock(); - set_root_rcu(nd); + nd->seq = set_root_rcu(nd); } else { set_root(nd); path_get(&nd->root); @@ -1903,7 +1906,14 @@ static int path_init(int dfd, const char *name, unsigned int flags, } nd->inode = nd->path.dentry->d_inode; - return 0; + if (!(flags & LOOKUP_RCU)) + return 0; + if (likely(!read_seqcount_retry(&nd->path.dentry->d_seq, nd->seq))) + return 0; + if (!(nd->flags & LOOKUP_ROOT)) + nd->root.mnt = NULL; + rcu_read_unlock(); + return -ECHILD; } static inline int lookup_last(struct nameidata *nd, struct path *path) |