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Authored By
mckusick
Apr 13 2015, 5:42 AM
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6 KB
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Index: kern/vfs_hash.c
===================================================================
--- kern/vfs_hash.c (revision 281469)
+++ kern/vfs_hash.c (working copy)
@@ -161,3 +161,39 @@
vp->v_hash = hash;
rw_wunlock(&vfs_hash_lock);
}
+
+void
+vfs_hash_changesize(int newhashsize)
+{
+ struct vfs_hash_head *vfs_hash_newtbl, *vfs_hash_oldtbl;
+ u_long vfs_hash_newmask, vfs_hash_oldmask;
+ struct vnode *vp;
+ int i;
+
+ vfs_hash_newtbl = hashinit(newhashsize, M_VFS_HASH, &vfs_hash_newmask);
+ /* If same hash table size, nothing to do */
+ if (vfs_hash_mask == vfs_hash_newmask) {
+ free(vfs_hash_newtbl, M_VFS_HASH);
+ return;
+ }
+ /*
+ * Move everything from the old hash table to the new table.
+ * None of the vnodes in the table can be recycled because to
+ * do so, they have to be removed from the hash table.
+ */
+ rw_wlock(&vfs_hash_lock);
+ vfs_hash_oldtbl = vfs_hash_tbl;
+ vfs_hash_oldmask = vfs_hash_mask;
+ vfs_hash_tbl = vfs_hash_newtbl;
+ vfs_hash_mask = vfs_hash_newmask;
+ for (i = 0; i <= vfs_hash_oldmask; i++) {
+ while ((vp = LIST_FIRST(&vfs_hash_oldtbl[i])) != NULL) {
+ LIST_REMOVE(vp, v_hashlist);
+ LIST_INSERT_HEAD(
+ vfs_hash_bucket(vp->v_mount, vp->v_hash),
+ vp, v_hashlist);
+ }
+ }
+ rw_wunlock(&vfs_hash_lock);
+ free(vfs_hash_oldtbl, M_VFS_HASH);
+}
Index: kern/vfs_cache.c
===================================================================
--- kern/vfs_cache.c (revision 281469)
+++ kern/vfs_cache.c (working copy)
@@ -96,6 +96,7 @@
TAILQ_ENTRY(namecache) nc_dst; /* destination vnode list */
struct vnode *nc_dvp; /* vnode of parent of name */
struct vnode *nc_vp; /* vnode the name refers to */
+ u_long nc_hashval; /* hash value used for hasing list */
u_char nc_flag; /* flag bits */
u_char nc_nlen; /* length of name */
char nc_name[0]; /* segment name + nul */
@@ -115,6 +116,7 @@
TAILQ_ENTRY(namecache) nc_dst; /* destination vnode list */
struct vnode *nc_dvp; /* vnode of parent of name */
struct vnode *nc_vp; /* vnode the name refers to */
+ u_long nc_hashval; /* hash value used for hasing list */
u_char nc_flag; /* flag bits */
u_char nc_nlen; /* length of name */
struct timespec nc_time; /* timespec provided by fs */
@@ -324,7 +326,7 @@
sysctl_debug_hashstat_rawnchash(SYSCTL_HANDLER_ARGS)
{
int error;
- struct nchashhead *ncpp;
+ struct nchashhead *ncpp, starthashtbl;
struct namecache *ncp;
int n_nchash;
int count;
@@ -334,8 +336,14 @@
return SYSCTL_OUT(req, 0, n_nchash * sizeof(int));
/* Scan hash tables for applicable entries */
+ starthashtbl = nchashtbl;
for (ncpp = nchashtbl; n_nchash > 0; n_nchash--, ncpp++) {
CACHE_RLOCK();
+ /* If the hash table gets replaced, give up */
+ if (starthashtbl != nchashtbl) {
+ CACHE_RUNLOCK();
+ return (EAGAIN);
+ }
count = 0;
LIST_FOREACH(ncp, ncpp, nc_hash) {
count++;
@@ -363,6 +371,7 @@
if (!req->oldptr)
return SYSCTL_OUT(req, 0, 4 * sizeof(int));
+ CACHE_RLOCK();
n_nchash = nchash + 1; /* nchash is max index, not count */
used = 0;
maxlength = 0;
@@ -370,17 +379,16 @@
/* Scan hash tables for applicable entries */
for (ncpp = nchashtbl; n_nchash > 0; n_nchash--, ncpp++) {
count = 0;
- CACHE_RLOCK();
LIST_FOREACH(ncp, ncpp, nc_hash) {
count++;
}
- CACHE_RUNLOCK();
if (count)
used++;
if (maxlength < count)
maxlength = count;
}
n_nchash = nchash + 1;
+ CACHE_RUNLOCK();
pct = (used * 100) / (n_nchash / 100);
error = SYSCTL_OUT(req, &n_nchash, sizeof(n_nchash));
if (error)
@@ -872,6 +880,7 @@
* Insert the new namecache entry into the appropriate chain
* within the cache entries table.
*/
+ ncp->nc_hashval = hash;
LIST_INSERT_HEAD(ncpp, ncp, nc_hash);
if (flag != NCF_ISDOTDOT) {
if (LIST_EMPTY(&dvp->v_cache_src)) {
@@ -934,7 +943,41 @@
}
SYSINIT(vfs, SI_SUB_VFS, SI_ORDER_SECOND, nchinit, NULL);
+void
+cache_changesize(int newhashsize)
+{
+ struct nchashhead *new_nchashtbl, *old_nchashtbl;
+ u_long new_nchash, old_nchash;
+ struct namecache *ncp;
+ int i;
+ new_nchashtbl = hashinit(newhashsize, M_VFSCACHE, &new_nchash);
+ /* If same hash table size, nothing to do */
+ if (nchash == new_nchash) {
+ free(new_nchashtbl, M_VFSCACHE);
+ return;
+ }
+ /*
+ * Move everything from the old hash table to the new table.
+ * None of the namecache entries in the table can be removed
+ * because to do so, they have to be removed from the hash table.
+ */
+ CACHE_WLOCK();
+ old_nchashtbl = nchashtbl;
+ old_nchash = nchash;
+ nchashtbl = new_nchashtbl;
+ nchash = new_nchash;
+ for (i = 0; i <= old_nchash; i++) {
+ while ((ncp = LIST_FIRST(&old_nchashtbl[i])) != NULL) {
+ LIST_REMOVE(ncp, nc_hash);
+ LIST_INSERT_HEAD(NCHHASH(ncp->nc_hashval), ncp,
+ nc_hash);
+ }
+ }
+ CACHE_WUNLOCK();
+ free(old_nchashtbl, M_VFSCACHE);
+}
+
/*
* Invalidate all entries to a particular vnode.
*/
Index: kern/vfs_subr.c
===================================================================
--- kern/vfs_subr.c (revision 281469)
+++ kern/vfs_subr.c (working copy)
@@ -275,8 +275,22 @@
* XXX desiredvnodes is historical cruft and should not exist.
*/
int desiredvnodes;
-SYSCTL_INT(_kern, KERN_MAXVNODES, maxvnodes, CTLFLAG_RW,
- &desiredvnodes, 0, "Maximum number of vnodes");
+
+static int
+sysctl_update_desiredvnodes(SYSCTL_HANDLER_ARGS)
+{
+ int error;
+
+ if ((error = sysctl_handle_int(oidp, arg1, arg2, req)) != 0)
+ return (error);
+ vfs_hash_changesize(desiredvnodes);
+ cache_changesize(desiredvnodes);
+ return (0);
+}
+
+SYSCTL_PROC(_kern, KERN_MAXVNODES, maxvnodes,
+ CTLTYPE_INT | CTLFLAG_MPSAFE | CTLFLAG_RW, &desiredvnodes, 0,
+ sysctl_update_desiredvnodes, "I", "Maximum number of vnodes");
SYSCTL_ULONG(_kern, OID_AUTO, minvnodes, CTLFLAG_RW,
&wantfreevnodes, 0, "Minimum number of vnodes (legacy)");
static int vnlru_nowhere;
Index: sys/vnode.h
===================================================================
--- sys/vnode.h (revision 281469)
+++ sys/vnode.h (working copy)
@@ -602,6 +602,7 @@
typedef int (*vn_get_ino_t)(struct mount *, void *, int, struct vnode **);
/* cache_* may belong in namei.h. */
+void cache_changesize(int newhashsize);
#define cache_enter(dvp, vp, cnp) \
cache_enter_time(dvp, vp, cnp, NULL, NULL)
void cache_enter_time(struct vnode *dvp, struct vnode *vp,
@@ -838,6 +839,7 @@
/* vfs_hash.c */
typedef int vfs_hash_cmp_t(struct vnode *vp, void *arg);
+void vfs_hash_changesize(int newhashsize);
int vfs_hash_get(const struct mount *mp, u_int hash, int flags, struct thread *td, struct vnode **vpp, vfs_hash_cmp_t *fn, void *arg);
u_int vfs_hash_index(struct vnode *vp);
int vfs_hash_insert(struct vnode *vp, u_int hash, int flags, struct thread *td, struct vnode **vpp, vfs_hash_cmp_t *fn, void *arg);

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