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-rw-r--r--fs/dcache.c173
-rw-r--r--fs/ext2/namei.c2
-rw-r--r--fs/ext3/namei.c2
-rw-r--r--fs/ext4/namei.c5
-rw-r--r--fs/gfs2/dir.c2
-rw-r--r--fs/libfs.c4
-rw-r--r--fs/namei.c19
-rw-r--r--fs/nfs/dir.c5
-rw-r--r--fs/nfs/nfs3proc.c3
-rw-r--r--fs/nfs/nfs4proc.c3
-rw-r--r--fs/nfs/proc.c3
-rw-r--r--fs/nilfs2/namei.c2
-rw-r--r--fs/ubifs/tnc.c2
-rw-r--r--fs/ubifs/xattr.c6
-rw-r--r--fs/udf/namei.c2
-rw-r--r--fs/ufs/super.c5
16 files changed, 146 insertions, 92 deletions
diff --git a/fs/dcache.c b/fs/dcache.c
index b80531c9177..92099f61bc6 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -153,16 +153,12 @@ int proc_nr_dentry(ctl_table *table, int write, void __user *buffer,
* In contrast, 'ct' and 'tcount' can be from a pathname, and do
* need the careful unaligned handling.
*/
-static inline int dentry_cmp(const unsigned char *cs, size_t scount,
- const unsigned char *ct, size_t tcount)
+static inline int dentry_string_cmp(const unsigned char *cs, const unsigned char *ct, unsigned tcount)
{
unsigned long a,b,mask;
- if (unlikely(scount != tcount))
- return 1;
-
for (;;) {
- a = load_unaligned_zeropad(cs);
+ a = *(unsigned long *)cs;
b = load_unaligned_zeropad(ct);
if (tcount < sizeof(unsigned long))
break;
@@ -180,12 +176,8 @@ static inline int dentry_cmp(const unsigned char *cs, size_t scount,
#else
-static inline int dentry_cmp(const unsigned char *cs, size_t scount,
- const unsigned char *ct, size_t tcount)
+static inline int dentry_string_cmp(const unsigned char *cs, const unsigned char *ct, unsigned tcount)
{
- if (scount != tcount)
- return 1;
-
do {
if (*cs != *ct)
return 1;
@@ -198,6 +190,27 @@ static inline int dentry_cmp(const unsigned char *cs, size_t scount,
#endif
+static inline int dentry_cmp(const struct dentry *dentry, const unsigned char *ct, unsigned tcount)
+{
+ /*
+ * Be careful about RCU walk racing with rename:
+ * use ACCESS_ONCE to fetch the name pointer.
+ *
+ * NOTE! Even if a rename will mean that the length
+ * was not loaded atomically, we don't care. The
+ * RCU walk will check the sequence count eventually,
+ * and catch it. And we won't overrun the buffer,
+ * because we're reading the name pointer atomically,
+ * and a dentry name is guaranteed to be properly
+ * terminated with a NUL byte.
+ *
+ * End result: even if 'len' is wrong, we'll exit
+ * early because the data cannot match (there can
+ * be no NUL in the ct/tcount data)
+ */
+ return dentry_string_cmp(ACCESS_ONCE(dentry->d_name.name), ct, tcount);
+}
+
static void __d_free(struct rcu_head *head)
{
struct dentry *dentry = container_of(head, struct dentry, d_u.d_rcu);
@@ -1439,18 +1452,18 @@ static struct dentry *__d_instantiate_unique(struct dentry *entry,
}
list_for_each_entry(alias, &inode->i_dentry, d_alias) {
- struct qstr *qstr = &alias->d_name;
-
/*
* Don't need alias->d_lock here, because aliases with
* d_parent == entry->d_parent are not subject to name or
* parent changes, because the parent inode i_mutex is held.
*/
- if (qstr->hash != hash)
+ if (alias->d_name.hash != hash)
continue;
if (alias->d_parent != entry->d_parent)
continue;
- if (dentry_cmp(qstr->name, qstr->len, name, len))
+ if (alias->d_name.len != len)
+ continue;
+ if (dentry_cmp(alias, name, len))
continue;
__dget(alias);
return alias;
@@ -1489,7 +1502,7 @@ struct dentry *d_make_root(struct inode *root_inode)
struct dentry *res = NULL;
if (root_inode) {
- static const struct qstr name = { .name = "/", .len = 1 };
+ static const struct qstr name = QSTR_INIT("/", 1);
res = __d_alloc(root_inode->i_sb, &name);
if (res)
@@ -1727,6 +1740,48 @@ err_out:
}
EXPORT_SYMBOL(d_add_ci);
+/*
+ * Do the slow-case of the dentry name compare.
+ *
+ * Unlike the dentry_cmp() function, we need to atomically
+ * load the name, length and inode information, so that the
+ * filesystem can rely on them, and can use the 'name' and
+ * 'len' information without worrying about walking off the
+ * end of memory etc.
+ *
+ * Thus the read_seqcount_retry() and the "duplicate" info
+ * in arguments (the low-level filesystem should not look
+ * at the dentry inode or name contents directly, since
+ * rename can change them while we're in RCU mode).
+ */
+enum slow_d_compare {
+ D_COMP_OK,
+ D_COMP_NOMATCH,
+ D_COMP_SEQRETRY,
+};
+
+static noinline enum slow_d_compare slow_dentry_cmp(
+ const struct dentry *parent,
+ struct inode *inode,
+ struct dentry *dentry,
+ unsigned int seq,
+ const struct qstr *name)
+{
+ int tlen = dentry->d_name.len;
+ const char *tname = dentry->d_name.name;
+ struct inode *i = dentry->d_inode;
+
+ if (read_seqcount_retry(&dentry->d_seq, seq)) {
+ cpu_relax();
+ return D_COMP_SEQRETRY;
+ }
+ if (parent->d_op->d_compare(parent, inode,
+ dentry, i,
+ tlen, tname, name))
+ return D_COMP_NOMATCH;
+ return D_COMP_OK;
+}
+
/**
* __d_lookup_rcu - search for a dentry (racy, store-free)
* @parent: parent dentry
@@ -1753,15 +1808,17 @@ EXPORT_SYMBOL(d_add_ci);
* the returned dentry, so long as its parent's seqlock is checked after the
* child is looked up. Thus, an interlocking stepping of sequence lock checks
* is formed, giving integrity down the path walk.
+ *
+ * NOTE! The caller *has* to check the resulting dentry against the sequence
+ * number we've returned before using any of the resulting dentry state!
*/
struct dentry *__d_lookup_rcu(const struct dentry *parent,
const struct qstr *name,
- unsigned *seqp, struct inode **inode)
+ unsigned *seqp, struct inode *inode)
{
- unsigned int len = name->len;
- unsigned int hash = name->hash;
+ u64 hashlen = name->hash_len;
const unsigned char *str = name->name;
- struct hlist_bl_head *b = d_hash(parent, hash);
+ struct hlist_bl_head *b = d_hash(parent, hashlen_hash(hashlen));
struct hlist_bl_node *node;
struct dentry *dentry;
@@ -1787,49 +1844,45 @@ struct dentry *__d_lookup_rcu(const struct dentry *parent,
*/
hlist_bl_for_each_entry_rcu(dentry, node, b, d_hash) {
unsigned seq;
- struct inode *i;
- const char *tname;
- int tlen;
-
- if (dentry->d_name.hash != hash)
- continue;
seqretry:
- seq = read_seqcount_begin(&dentry->d_seq);
- if (dentry->d_parent != parent)
- continue;
- if (d_unhashed(dentry))
- continue;
- tlen = dentry->d_name.len;
- tname = dentry->d_name.name;
- i = dentry->d_inode;
- prefetch(tname);
/*
- * This seqcount check is required to ensure name and
- * len are loaded atomically, so as not to walk off the
- * edge of memory when walking. If we could load this
- * atomically some other way, we could drop this check.
+ * The dentry sequence count protects us from concurrent
+ * renames, and thus protects inode, parent and name fields.
+ *
+ * The caller must perform a seqcount check in order
+ * to do anything useful with the returned dentry,
+ * including using the 'd_inode' pointer.
+ *
+ * NOTE! We do a "raw" seqcount_begin here. That means that
+ * we don't wait for the sequence count to stabilize if it
+ * is in the middle of a sequence change. If we do the slow
+ * dentry compare, we will do seqretries until it is stable,
+ * and if we end up with a successful lookup, we actually
+ * want to exit RCU lookup anyway.
*/
- if (read_seqcount_retry(&dentry->d_seq, seq))
- goto seqretry;
+ seq = raw_seqcount_begin(&dentry->d_seq);
+ if (dentry->d_parent != parent)
+ continue;
+ *seqp = seq;
+
if (unlikely(parent->d_flags & DCACHE_OP_COMPARE)) {
- if (parent->d_op->d_compare(parent, *inode,
- dentry, i,
- tlen, tname, name))
+ if (dentry->d_name.hash != hashlen_hash(hashlen))
continue;
- } else {
- if (dentry_cmp(tname, tlen, str, len))
+ switch (slow_dentry_cmp(parent, inode, dentry, seq, name)) {
+ case D_COMP_OK:
+ return dentry;
+ case D_COMP_NOMATCH:
continue;
+ default:
+ goto seqretry;
+ }
}
- /*
- * No extra seqcount check is required after the name
- * compare. The caller must perform a seqcount check in
- * order to do anything useful with the returned dentry
- * anyway.
- */
- *seqp = seq;
- *inode = i;
- return dentry;
+
+ if (dentry->d_name.hash_len != hashlen)
+ continue;
+ if (!dentry_cmp(dentry, str, hashlen_len(hashlen)))
+ return dentry;
}
return NULL;
}
@@ -1908,8 +1961,6 @@ struct dentry *__d_lookup(struct dentry *parent, struct qstr *name)
rcu_read_lock();
hlist_bl_for_each_entry_rcu(dentry, node, b, d_hash) {
- const char *tname;
- int tlen;
if (dentry->d_name.hash != hash)
continue;
@@ -1924,15 +1975,17 @@ struct dentry *__d_lookup(struct dentry *parent, struct qstr *name)
* It is safe to compare names since d_move() cannot
* change the qstr (protected by d_lock).
*/
- tlen = dentry->d_name.len;
- tname = dentry->d_name.name;
if (parent->d_flags & DCACHE_OP_COMPARE) {
+ int tlen = dentry->d_name.len;
+ const char *tname = dentry->d_name.name;
if (parent->d_op->d_compare(parent, parent->d_inode,
dentry, dentry->d_inode,
tlen, tname, name))
goto next;
} else {
- if (dentry_cmp(tname, tlen, str, len))
+ if (dentry->d_name.len != len)
+ goto next;
+ if (dentry_cmp(dentry, str, len))
goto next;
}
diff --git a/fs/ext2/namei.c b/fs/ext2/namei.c
index dffb8653628..f663a67d7bf 100644
--- a/fs/ext2/namei.c
+++ b/fs/ext2/namei.c
@@ -79,7 +79,7 @@ static struct dentry *ext2_lookup(struct inode * dir, struct dentry *dentry, str
struct dentry *ext2_get_parent(struct dentry *child)
{
- struct qstr dotdot = {.name = "..", .len = 2};
+ struct qstr dotdot = QSTR_INIT("..", 2);
unsigned long ino = ext2_inode_by_name(child->d_inode, &dotdot);
if (!ino)
return ERR_PTR(-ENOENT);
diff --git a/fs/ext3/namei.c b/fs/ext3/namei.c
index d7940b24cf6..eeb63dfc5d2 100644
--- a/fs/ext3/namei.c
+++ b/fs/ext3/namei.c
@@ -1045,7 +1045,7 @@ static struct dentry *ext3_lookup(struct inode * dir, struct dentry *dentry, str
struct dentry *ext3_get_parent(struct dentry *child)
{
unsigned long ino;
- struct qstr dotdot = {.name = "..", .len = 2};
+ struct qstr dotdot = QSTR_INIT("..", 2);
struct ext3_dir_entry_2 * de;
struct buffer_head *bh;
diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
index 349d7b3671c..e2a3f4b0ff7 100644
--- a/fs/ext4/namei.c
+++ b/fs/ext4/namei.c
@@ -1052,10 +1052,7 @@ static struct dentry *ext4_lookup(struct inode *dir, struct dentry *dentry, stru
struct dentry *ext4_get_parent(struct dentry *child)
{
__u32 ino;
- static const struct qstr dotdot = {
- .name = "..",
- .len = 2,
- };
+ static const struct qstr dotdot = QSTR_INIT("..", 2);
struct ext4_dir_entry_2 * de;
struct buffer_head *bh;
diff --git a/fs/gfs2/dir.c b/fs/gfs2/dir.c
index a836056343f..8aaeb07a07b 100644
--- a/fs/gfs2/dir.c
+++ b/fs/gfs2/dir.c
@@ -821,7 +821,7 @@ static struct gfs2_leaf *new_leaf(struct inode *inode, struct buffer_head **pbh,
struct buffer_head *bh;
struct gfs2_leaf *leaf;
struct gfs2_dirent *dent;
- struct qstr name = { .name = "", .len = 0, .hash = 0 };
+ struct qstr name = { .name = "" };
error = gfs2_alloc_blocks(ip, &bn, &n, 0, NULL);
if (error)
diff --git a/fs/libfs.c b/fs/libfs.c
index 18d08f5db53..f86ec27a423 100644
--- a/fs/libfs.c
+++ b/fs/libfs.c
@@ -68,7 +68,7 @@ struct dentry *simple_lookup(struct inode *dir, struct dentry *dentry, struct na
int dcache_dir_open(struct inode *inode, struct file *file)
{
- static struct qstr cursor_name = {.len = 1, .name = "."};
+ static struct qstr cursor_name = QSTR_INIT(".", 1);
file->private_data = d_alloc(file->f_path.dentry, &cursor_name);
@@ -225,7 +225,7 @@ struct dentry *mount_pseudo(struct file_system_type *fs_type, char *name,
struct super_block *s = sget(fs_type, NULL, set_anon_super, NULL);
struct dentry *dentry;
struct inode *root;
- struct qstr d_name = {.name = name, .len = strlen(name)};
+ struct qstr d_name = QSTR_INIT(name, strlen(name));
if (IS_ERR(s))
return ERR_CAST(s);
diff --git a/fs/namei.c b/fs/namei.c
index 709fb2c17b5..f9e883c1b85 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -1144,12 +1144,25 @@ static int do_lookup(struct nameidata *nd, struct qstr *name,
*/
if (nd->flags & LOOKUP_RCU) {
unsigned seq;
- *inode = nd->inode;
- dentry = __d_lookup_rcu(parent, name, &seq, inode);
+ dentry = __d_lookup_rcu(parent, name, &seq, nd->inode);
if (!dentry)
goto unlazy;
- /* Memory barrier in read_seqcount_begin of child is enough */
+ /*
+ * This sequence count validates that the inode matches
+ * the dentry name information from lookup.
+ */
+ *inode = dentry->d_inode;
+ if (read_seqcount_retry(&dentry->d_seq, seq))
+ return -ECHILD;
+
+ /*
+ * This sequence count validates that the parent had no
+ * changes while we did the lookup of the dentry above.
+ *
+ * The memory barrier in read_seqcount_begin of child is
+ * enough, we can use __read_seqcount_retry here.
+ */
if (__read_seqcount_retry(&parent->d_seq, nd->seq))
return -ECHILD;
nd->seq = seq;
diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
index 8789210c690..eedd24d0ad2 100644
--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -477,10 +477,7 @@ different:
static
void nfs_prime_dcache(struct dentry *parent, struct nfs_entry *entry)
{
- struct qstr filename = {
- .len = entry->len,
- .name = entry->name,
- };
+ struct qstr filename = QSTR_INIT(entry->name, entry->len);
struct dentry *dentry;
struct dentry *alias;
struct inode *dir = parent->d_inode;
diff --git a/fs/nfs/nfs3proc.c b/fs/nfs/nfs3proc.c
index 5242eae6711..75c68299358 100644
--- a/fs/nfs/nfs3proc.c
+++ b/fs/nfs/nfs3proc.c
@@ -398,8 +398,7 @@ nfs3_proc_remove(struct inode *dir, struct qstr *name)
{
struct nfs_removeargs arg = {
.fh = NFS_FH(dir),
- .name.len = name->len,
- .name.name = name->name,
+ .name = *name,
};
struct nfs_removeres res;
struct rpc_message msg = {
diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index 99650aaf893..ab985f6f0da 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -2782,8 +2782,7 @@ static int _nfs4_proc_remove(struct inode *dir, struct qstr *name)
struct nfs_server *server = NFS_SERVER(dir);
struct nfs_removeargs args = {
.fh = NFS_FH(dir),
- .name.len = name->len,
- .name.name = name->name,
+ .name = *name,
.bitmask = server->attr_bitmask,
};
struct nfs_removeres res = {
diff --git a/fs/nfs/proc.c b/fs/nfs/proc.c
index b63b6f4d14f..d6408b6437d 100644
--- a/fs/nfs/proc.c
+++ b/fs/nfs/proc.c
@@ -335,8 +335,7 @@ nfs_proc_remove(struct inode *dir, struct qstr *name)
{
struct nfs_removeargs arg = {
.fh = NFS_FH(dir),
- .name.len = name->len,
- .name.name = name->name,
+ .name = *name,
};
struct rpc_message msg = {
.rpc_proc = &nfs_procedures[NFSPROC_REMOVE],
diff --git a/fs/nilfs2/namei.c b/fs/nilfs2/namei.c
index fce2bbee66d..0bb2c2010b9 100644
--- a/fs/nilfs2/namei.c
+++ b/fs/nilfs2/namei.c
@@ -441,7 +441,7 @@ static struct dentry *nilfs_get_parent(struct dentry *child)
{
unsigned long ino;
struct inode *inode;
- struct qstr dotdot = {.name = "..", .len = 2};
+ struct qstr dotdot = QSTR_INIT("..", 2);
struct nilfs_root *root;
ino = nilfs_inode_by_name(child->d_inode, &dotdot);
diff --git a/fs/ubifs/tnc.c b/fs/ubifs/tnc.c
index 16ad84d8402..abd51331345 100644
--- a/fs/ubifs/tnc.c
+++ b/fs/ubifs/tnc.c
@@ -2361,7 +2361,7 @@ int ubifs_tnc_add_nm(struct ubifs_info *c, const union ubifs_key *key,
* by passing 'ubifs_tnc_remove_nm()' the same key but
* an unmatchable name.
*/
- struct qstr noname = { .len = 0, .name = "" };
+ struct qstr noname = { .name = "" };
err = dbg_check_tnc(c, 0);
mutex_unlock(&c->tnc_mutex);
diff --git a/fs/ubifs/xattr.c b/fs/ubifs/xattr.c
index 85b27226875..7a8bafa19c9 100644
--- a/fs/ubifs/xattr.c
+++ b/fs/ubifs/xattr.c
@@ -298,7 +298,7 @@ int ubifs_setxattr(struct dentry *dentry, const char *name,
{
struct inode *inode, *host = dentry->d_inode;
struct ubifs_info *c = host->i_sb->s_fs_info;
- struct qstr nm = { .name = name, .len = strlen(name) };
+ struct qstr nm = QSTR_INIT(name, strlen(name));
struct ubifs_dent_node *xent;
union ubifs_key key;
int err, type;
@@ -361,7 +361,7 @@ ssize_t ubifs_getxattr(struct dentry *dentry, const char *name, void *buf,
{
struct inode *inode, *host = dentry->d_inode;
struct ubifs_info *c = host->i_sb->s_fs_info;
- struct qstr nm = { .name = name, .len = strlen(name) };
+ struct qstr nm = QSTR_INIT(name, strlen(name));
struct ubifs_inode *ui;
struct ubifs_dent_node *xent;
union ubifs_key key;
@@ -524,7 +524,7 @@ int ubifs_removexattr(struct dentry *dentry, const char *name)
{
struct inode *inode, *host = dentry->d_inode;
struct ubifs_info *c = host->i_sb->s_fs_info;
- struct qstr nm = { .name = name, .len = strlen(name) };
+ struct qstr nm = QSTR_INIT(name, strlen(name));
struct ubifs_dent_node *xent;
union ubifs_key key;
int err;
diff --git a/fs/udf/namei.c b/fs/udf/namei.c
index 38de8f234b9..a165c66e3ee 100644
--- a/fs/udf/namei.c
+++ b/fs/udf/namei.c
@@ -1193,7 +1193,7 @@ static struct dentry *udf_get_parent(struct dentry *child)
{
struct kernel_lb_addr tloc;
struct inode *inode = NULL;
- struct qstr dotdot = {.name = "..", .len = 2};
+ struct qstr dotdot = QSTR_INIT("..", 2);
struct fileIdentDesc cfi;
struct udf_fileident_bh fibh;
diff --git a/fs/ufs/super.c b/fs/ufs/super.c
index ac8e279eccc..302f340d007 100644
--- a/fs/ufs/super.c
+++ b/fs/ufs/super.c
@@ -146,10 +146,7 @@ static struct dentry *ufs_fh_to_parent(struct super_block *sb, struct fid *fid,
static struct dentry *ufs_get_parent(struct dentry *child)
{
- struct qstr dot_dot = {
- .name = "..",
- .len = 2,
- };
+ struct qstr dot_dot = QSTR_INIT("..", 2);
ino_t ino;
ino = ufs_inode_by_name(child->d_inode, &dot_dot);
generated by cgit v1.2.3-70-g09d2 (git 2.46.0) at 2024-12-03 15:58:19 +0000