Don't pass inode to ->d_hash() and ->d_compare()
Instances either don't look at it at all (the majority of cases) or
only want it to find the superblock (which can be had as dentry->d_sb).
A few cases that want more are actually safe with dentry->d_inode -
the only precaution needed is the check that it hadn't been replaced with
NULL by rmdir() or by overwriting rename(), which case should be simply
treated as cache miss.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/dcache.c b/fs/dcache.c
index b692c7e..3199fe6 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -1723,7 +1723,7 @@
* 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
+ * load the name and length 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.
@@ -1741,22 +1741,18 @@
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))
+ if (parent->d_op->d_compare(parent, dentry, tlen, tname, name))
return D_COMP_NOMATCH;
return D_COMP_OK;
}
@@ -1766,7 +1762,6 @@
* @parent: parent dentry
* @name: qstr of name we wish to find
* @seqp: returns d_seq value at the point where the dentry was found
- * @inode: returns dentry->d_inode when the inode was found valid.
* Returns: dentry, or NULL
*
* __d_lookup_rcu is the dcache lookup function for rcu-walk name
@@ -1793,7 +1788,7 @@
*/
struct dentry *__d_lookup_rcu(const struct dentry *parent,
const struct qstr *name,
- unsigned *seqp, struct inode *inode)
+ unsigned *seqp)
{
u64 hashlen = name->hash_len;
const unsigned char *str = name->name;
@@ -1827,11 +1822,10 @@
seqretry:
/*
* The dentry sequence count protects us from concurrent
- * renames, and thus protects inode, parent and name fields.
+ * renames, and thus protects 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.
+ * to do anything useful with the returned dentry.
*
* NOTE! We do a "raw" seqcount_begin here. That means that
* we don't wait for the sequence count to stabilize if it
@@ -1845,12 +1839,12 @@
continue;
if (d_unhashed(dentry))
continue;
- *seqp = seq;
if (unlikely(parent->d_flags & DCACHE_OP_COMPARE)) {
if (dentry->d_name.hash != hashlen_hash(hashlen))
continue;
- switch (slow_dentry_cmp(parent, inode, dentry, seq, name)) {
+ *seqp = seq;
+ switch (slow_dentry_cmp(parent, dentry, seq, name)) {
case D_COMP_OK:
return dentry;
case D_COMP_NOMATCH:
@@ -1862,6 +1856,7 @@
if (dentry->d_name.hash_len != hashlen)
continue;
+ *seqp = seq;
if (!dentry_cmp(dentry, str, hashlen_len(hashlen)))
return dentry;
}
@@ -1959,9 +1954,7 @@
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))
+ if (parent->d_op->d_compare(parent, dentry, tlen, tname, name))
goto next;
} else {
if (dentry->d_name.len != len)
@@ -1998,7 +1991,7 @@
*/
name->hash = full_name_hash(name->name, name->len);
if (dir->d_flags & DCACHE_OP_HASH) {
- int err = dir->d_op->d_hash(dir, dir->d_inode, name);
+ int err = dir->d_op->d_hash(dir, name);
if (unlikely(err < 0))
return ERR_PTR(err);
}