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-rw-r--r--fs/namei.c96
1 files changed, 53 insertions, 43 deletions
diff --git a/fs/namei.c b/fs/namei.c
index a996bb48dfab..a7b05bf82d31 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -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)
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