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SubjectRe: [PATCH] Re: Major XFS problems...
On Fri, Sep 17, 2004 at 01:26:47PM +0200, Jakob Oestergaard wrote:
> In the light of all this, I would like to suggest that the following
> patch is included in mainline - it is the old patch from Neil Brown
> (http://marc.theaimsgroup.com/?l=linux-kernel&m=108330112505555&w=2)
> adapted by me for 2.6.8.1 (this patch was attached to a previous mail
> from me in this thread as well):


Neil, any chance we could get this patch into mainline ASAP? Without
it we get ->get_parent called on non-directories under heavy NFS loads..


--- fs/dcache.c.orig Sat Aug 14 12:54:50 2004
+++ fs/dcache.c Thu Sep 9 15:56:04 2004
@@ -286,12 +286,11 @@
* any other hashed alias over that one.
*/

-struct dentry * d_find_alias(struct inode *inode)
+static struct dentry * __d_find_alias(struct inode *inode, int want_discon)
{
struct list_head *head, *next, *tmp;
struct dentry *alias, *discon_alias=NULL;

- spin_lock(&dcache_lock);
head = &inode->i_dentry;
next = inode->i_dentry.next;
while (next != head) {
@@ -302,19 +301,26 @@
if (!d_unhashed(alias)) {
if (alias->d_flags & DCACHE_DISCONNECTED)
discon_alias = alias;
- else {
+ else if (!want_discon) {
__dget_locked(alias);
- spin_unlock(&dcache_lock);
return alias;
}
}
}
if (discon_alias)
__dget_locked(discon_alias);
- spin_unlock(&dcache_lock);
return discon_alias;
}

+struct dentry * d_find_alias(struct inode *inode)
+{
+ struct dentry *de;
+ spin_lock(&dcache_lock);
+ de = __d_find_alias(inode, 0);
+ spin_unlock(&dcache_lock);
+ return de;
+}
+
/*
* Try to kill dentries associated with this inode.
* WARNING: you must own a reference to inode.
@@ -833,33 +839,27 @@
tmp->d_parent = tmp; /* make sure dput doesn't croak */

spin_lock(&dcache_lock);
- if (S_ISDIR(inode->i_mode) && !list_empty(&inode->i_dentry)) {
- /* A directory can only have one dentry.
- * This (now) has one, so use it.
- */
- res = list_entry(inode->i_dentry.next, struct dentry, d_alias);
- __dget_locked(res);
- } else {
+ res = __d_find_alias(inode, 0);
+ if (!res) {
/* attach a disconnected dentry */
res = tmp;
tmp = NULL;
- if (res) {
- spin_lock(&res->d_lock);
- res->d_sb = inode->i_sb;
- res->d_parent = res;
- res->d_inode = inode;
+ spin_lock(&res->d_lock);
+ res->d_sb = inode->i_sb;
+ res->d_parent = res;
+ res->d_inode = inode;
+
+ /*
+ * Set d_bucket to an "impossible" bucket address so
+ * that d_move() doesn't get a false positive
+ */
+ res->d_bucket = NULL;
+ res->d_flags |= DCACHE_DISCONNECTED;
+ res->d_flags &= ~DCACHE_UNHASHED;
+ list_add(&res->d_alias, &inode->i_dentry);
+ hlist_add_head(&res->d_hash, &inode->i_sb->s_anon);
+ spin_unlock(&res->d_lock);

- /*
- * Set d_bucket to an "impossible" bucket address so
- * that d_move() doesn't get a false positive
- */
- res->d_bucket = NULL;
- res->d_flags |= DCACHE_DISCONNECTED;
- res->d_flags &= ~DCACHE_UNHASHED;
- list_add(&res->d_alias, &inode->i_dentry);
- hlist_add_head(&res->d_hash, &inode->i_sb->s_anon);
- spin_unlock(&res->d_lock);
- }
inode = NULL; /* don't drop reference */
}
spin_unlock(&dcache_lock);
@@ -881,7 +881,7 @@
* DCACHE_DISCONNECTED), then d_move that in place of the given dentry
* and return it, else simply d_add the inode to the dentry and return NULL.
*
- * This is (will be) needed in the lookup routine of any filesystem that is exportable
+ * This is needed in the lookup routine of any filesystem that is exportable
* (via knfsd) so that we can build dcache paths to directories effectively.
*
* If a dentry was found and moved, then it is returned. Otherwise NULL
@@ -892,11 +892,11 @@
{
struct dentry *new = NULL;

- if (inode && S_ISDIR(inode->i_mode)) {
+ if (inode) {
spin_lock(&dcache_lock);
- if (!list_empty(&inode->i_dentry)) {
- new = list_entry(inode->i_dentry.next, struct dentry, d_alias);
- __dget_locked(new);
+ new = __d_find_alias(inode, 1);
+ if (new) {
+ BUG_ON(!(new->d_flags & DCACHE_DISCONNECTED));
spin_unlock(&dcache_lock);
security_d_instantiate(new, inode);
d_rehash(dentry);

PS: I'll be without internet access from now until sunday the 26th - if
there are comments or questions, please make sure they are sent to this
list and/or as@cohaesio.com - Anders can get in touch with me if
necessary.


--

/ jakob

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