DragonFly kernel List (threaded) for 2008-01
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Patch for inode SLIST conversion
Hi,
Appended my first patch. And it wasn't that hard at all. The Projects
page of the DF wiki mentioned to convert the inode i_next field to use a
SLIST. This is what the patch does. I'm not sure if it is that usable :)
I introduced a SLIST_FOREACH_WITH_PREV macro which keeps a pointer to
the previous element around in each iteration. That's quite usable if
you want to insert an element somewhere (just break out of the for loop
and use SLIST_NEXT(prev) = new_element).
Regards,
Michael
Index: sys/vfs/ufs/inode.h
===================================================================
RCS file: /home/dcvs/src/sys/vfs/ufs/inode.h,v
retrieving revision 1.12
diff -u -r1.12 inode.h
--- sys/vfs/ufs/inode.h 10 Sep 2006 01:26:41 -0000 1.12
+++ sys/vfs/ufs/inode.h 18 Jan 2008 17:34:23 -0000
@@ -81,7 +81,7 @@
* active, and is put back when the file is no longer being used.
*/
struct inode {
- struct inode *i_next;/* Hash chain */
+ SLIST_ENTRY(inode) i_next;/* Hash chain */
struct vnode *i_vnode;/* Vnode associated with this inode. */
struct vnode *i_devvp;/* Vnode for block I/O. */
uint32_t i_flag; /* flags, see below */
Index: sys/vfs/ufs/ufs_ihash.c
===================================================================
RCS file: /home/dcvs/src/sys/vfs/ufs/ufs_ihash.c,v
retrieving revision 1.20
diff -u -r1.20 ufs_ihash.c
--- sys/vfs/ufs/ufs_ihash.c 14 Oct 2006 16:26:40 -0000 1.20
+++ sys/vfs/ufs/ufs_ihash.c 18 Jan 2008 19:24:49 -0000
@@ -51,13 +51,23 @@
/*
* Structures associated with inode cacheing.
*/
-static struct inode **ihashtbl;
+SLIST_HEAD(ihashtbl_bucket, inode);
+static struct ihashtbl_bucket *ihashtbl;
static u_long ihash; /* size of hash table - 1 */
static struct lwkt_token ufs_ihash_token;
#define INOHASH(device, inum) (&ihashtbl[(minor(device) + (inum)) & ihash])
/*
+ * Keeps the previous element around while iterating through the list.
+ */
+#define SLIST_FOREACH_WITH_PREV(var, prev, head, field) \
+ for (((prev) = NULL, (var) = SLIST_FIRST((head))); \
+ (var); \
+ ((prev) = (var), (var) = SLIST_NEXT((var), field)))
+
+
+/*
* Initialize inode hash table.
*/
void
@@ -66,7 +76,7 @@
ihash = 16;
while (ihash < desiredvnodes)
ihash <<= 1;
- ihashtbl = kmalloc(sizeof(void *) * ihash, M_UFSIHASH, M_WAITOK|M_ZERO);
+ ihashtbl = kmalloc(sizeof(struct ihashtbl_bucket) * ihash, M_UFSIHASH, M_WAITOK|M_ZERO);
--ihash;
lwkt_token_init(&ufs_ihash_token);
}
@@ -94,7 +104,8 @@
lwkt_tokref ilock;
lwkt_gettoken(&ilock, &ufs_ihash_token);
- for (ip = *INOHASH(dev, inum); ip; ip = ip->i_next) {
+
+ SLIST_FOREACH(ip, INOHASH(dev, inum), i_next) {
if (inum == ip->i_number && dev == ip->i_dev)
break;
}
@@ -122,7 +133,7 @@
lwkt_gettoken(&ilock, &ufs_ihash_token);
loop:
- for (ip = *INOHASH(dev, inum); ip; ip = ip->i_next) {
+ SLIST_FOREACH(ip, INOHASH(dev, inum), i_next) {
if (inum != ip->i_number || dev != ip->i_dev)
continue;
vp = ITOV(ip);
@@ -132,7 +143,7 @@
* We must check to see if the inode has been ripped
* out from under us after blocking.
*/
- for (ip = *INOHASH(dev, inum); ip; ip = ip->i_next) {
+ SLIST_FOREACH(ip, INOHASH(dev, inum), i_next) {
if (inum == ip->i_number && dev == ip->i_dev)
break;
}
@@ -159,7 +170,7 @@
struct inode *ip;
lwkt_gettoken(&ilock, &ufs_ihash_token);
- for (ip = *INOHASH(dev, inum); ip; ip = ip->i_next) {
+ SLIST_FOREACH(ip, INOHASH(dev, inum), i_next) {
if (inum == ip->i_number && dev == ip->i_dev)
break;
}
@@ -173,22 +184,24 @@
int
ufs_ihashins(struct inode *ip)
{
- struct inode **ipp;
struct inode *iq;
+ struct inode *prev;
+ struct ihashtbl_bucket *head;
lwkt_tokref ilock;
KKASSERT((ip->i_flag & IN_HASHED) == 0);
lwkt_gettoken(&ilock, &ufs_ihash_token);
- ipp = INOHASH(ip->i_dev, ip->i_number);
- while ((iq = *ipp) != NULL) {
+
+ head = INOHASH(ip->i_dev, ip->i_number);
+ SLIST_FOREACH_WITH_PREV(iq, prev, head, i_next) {
if (ip->i_dev == iq->i_dev && ip->i_number == iq->i_number) {
lwkt_reltoken(&ilock);
return(EBUSY);
}
- ipp = &iq->i_next;
}
- ip->i_next = NULL;
- *ipp = ip;
+ if (prev) SLIST_NEXT(prev, i_next) = ip;
+ else SLIST_FIRST(head) = ip;
+ SLIST_NEXT(ip, i_next) = NULL;
ip->i_flag |= IN_HASHED;
lwkt_reltoken(&ilock);
return(0);
@@ -201,20 +214,11 @@
ufs_ihashrem(struct inode *ip)
{
lwkt_tokref ilock;
- struct inode **ipp;
- struct inode *iq;
lwkt_gettoken(&ilock, &ufs_ihash_token);
if (ip->i_flag & IN_HASHED) {
- ipp = INOHASH(ip->i_dev, ip->i_number);
- while ((iq = *ipp) != NULL) {
- if (ip == iq)
- break;
- ipp = &iq->i_next;
- }
- KKASSERT(ip == iq);
- *ipp = ip->i_next;
- ip->i_next = NULL;
+ SLIST_REMOVE(INOHASH(ip->i_dev, ip->i_number), ip, inode, i_next);
+ SLIST_NEXT(ip, i_next) = NULL;
ip->i_flag &= ~IN_HASHED;
}
lwkt_reltoken(&ilock);
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