Appended here is the dcache scalability patch for 2.5 version with
performance numbers for dbench. dcache_rcu-12 gives consistently better results
than base.
The patch can be downloaded from lse site at
http://prdownloads.sourceforge.net/lse/dcache_rcu-12-2.5.30.patch?download
The patch essentially does faster d_lookup() by not taking the global
dcache_lock and significantly brings down the contention for dcache_lock,
that is by 85%
While pathwalk'ing the dcache_lock is not held and dentires are kept
around by incrementing the ref count. This also helps in reducing the
hold time for dcache_lock by more than 50%.
dbench throughput (MB/sec) for varying #s of clients on 8-way
2.5.30 dcache_rcu-12
====== ======
1 78.76 81.43
2 139.06 140.28
4 218.9 227.43
8 241.64 246.8
10 255.56 258.34
12 255.89 260.66
16 246.57 252.97
18 250.82 249.79
20 252.05 251.59
24 243.03 248.12
32 243.17 244.87
48 227.09 240.98
64 209.62 239.52
128 59.17 55.97
http://lse.sourceforge.net/locking/dcache/results/2.5.30/dbench/8-way.png
dbench Throughput (MB/sec) for 12 clients
2.5.30 2.5.30 + dcache_rcu-12
====== =======
Uni 82.405 82.65241
2-way SMP 141.914 141.1884
4-way SMP 226.664 227.287
8-way SMP 256.064 260.4548
http://lse.sourceforge.net/locking/dcache/results/2.5.30/dbench/cpus-thruput.png
Lockmeter statistics show reduction in dcache_lock contention, utilization
and hold times.
Base (2.5.30)
=============
SPINLOCKS HOLD WAIT
UTIL CON MEAN( MAX ) MEAN( MAX )(% CPU) TOTAL NOWAIT SPIN RJECT NAME
3.3% 7.8% 2.1us(2437us) 4.8us(2415us)(0.02%) 309088 92.2% 7.8% 0% dcache_lock
dcache_rcu-12
=============
0.60% 1.1% 1.0us(1108us) 6.0us(1260us)(0.00%) 112929 98.9% 1.1% 0% dcache_lock
Detailed lockmeter report
http://lse.sourceforge.net/locking/dcache/results/2.5.30/dbench/baselkm-2.5.30
http://lse.sourceforge.net/locking/dcache/results/2.5.30/dbench/dc12lkm-2.5.30
Regards,
Maneesh
-- Maneesh Soni IBM Linux Technology Center, IBM India Software Lab, Bangalore. Phone: +91-80-5044999 email: maneesh@in.ibm.com http://lse.sourceforge.net/locking/rcupdate.html
dcache_rcu-12-2.5.31.patch -------------------------- Changes in this version: o Instead of entierly backing out fastwalk code to 2.5.10 level, this patch brings the dcache_lock down to d_lookup level and has lesser changes. o has to put back per dentry lock because of a race in dcache_rcu-11 in d_delete.
diff -urN linux-2.5.30-base/fs/autofs4/root.c linux-2.5.30-dc12/fs/autofs4/root.c --- linux-2.5.30-base/fs/autofs4/root.c Fri Aug 2 02:46:03 2002 +++ linux-2.5.30-dc12/fs/autofs4/root.c Fri Aug 2 17:03:18 2002 @@ -418,7 +418,7 @@ unlock_kernel(); return -ENOTEMPTY; } - list_del_init(&dentry->d_hash); + __d_drop(dentry); spin_unlock(&dcache_lock); dput(ino->dentry); diff -urN linux-2.5.30-base/fs/dcache.c linux-2.5.30-dc12/fs/dcache.c --- linux-2.5.30-base/fs/dcache.c Fri Aug 2 02:46:08 2002 +++ linux-2.5.30-dc12/fs/dcache.c Fri Aug 2 17:03:18 2002 @@ -23,6 +23,7 @@ #include <linux/smp_lock.h> #include <linux/cache.h> #include <linux/module.h> +#include <linux/rcupdate.h> #include <asm/uaccess.h> @@ -53,14 +54,21 @@ /* Statistics gathering. */ struct dentry_stat_t dentry_stat = {0, 0, 45, 0,}; +static void d_callback(void *arg) +{ + struct dentry * dentry = (struct dentry *)arg; + + if (dname_external(dentry)) + kfree(dentry->d_name.name); + kmem_cache_free(dentry_cache, dentry); +} + /* no dcache_lock, please */ static inline void d_free(struct dentry *dentry) { if (dentry->d_op && dentry->d_op->d_release) dentry->d_op->d_release(dentry); - if (dname_external(dentry)) - kfree(dentry->d_name.name); - kmem_cache_free(dentry_cache, dentry); + call_rcu(&dentry->d_rcu, d_callback, dentry); dentry_stat.nr_dentry--; } @@ -122,9 +130,13 @@ if (!atomic_dec_and_lock(&dentry->d_count, &dcache_lock)) return; - /* dput on a free dentry? */ - if (!list_empty(&dentry->d_lru)) - BUG(); + spin_lock(&dentry->d_lock); + if (atomic_read(&dentry->d_count)) { + spin_unlock(&dentry->d_lock); + spin_unlock(&dcache_lock); + return; + } + /* * AV: ->d_delete() is _NOT_ allowed to block now. */ @@ -133,20 +145,29 @@ goto unhash_it; } /* Unreachable? Get rid of it */ - if (list_empty(&dentry->d_hash)) + if (d_unhashed(dentry)) goto kill_it; - list_add(&dentry->d_lru, &dentry_unused); - dentry_stat.nr_unused++; - dentry->d_vfs_flags |= DCACHE_REFERENCED; + if (list_empty(&dentry->d_lru)) { + dentry->d_vfs_flags &= ~DCACHE_REFERENCED; + list_add(&dentry->d_lru, &dentry_unused); + dentry_stat.nr_unused++; + } + spin_unlock(&dentry->d_lock); spin_unlock(&dcache_lock); return; unhash_it: - list_del_init(&dentry->d_hash); + dentry->d_vfs_flags |= DCACHE_UNHASHED; + list_del_rcu(&dentry->d_hash); kill_it: { struct dentry *parent; + if (!list_empty(&dentry->d_lru)) { + list_del(&dentry->d_lru); + dentry_stat.nr_unused--; + } list_del(&dentry->d_child); + spin_unlock(&dentry->d_lock); /* drops the lock, at that point nobody can reach this dentry */ dentry_iput(dentry); parent = dentry->d_parent; @@ -176,7 +197,7 @@ * If it's already been dropped, return OK. */ spin_lock(&dcache_lock); - if (list_empty(&dentry->d_hash)) { + if (d_unhashed(dentry)) { spin_unlock(&dcache_lock); return 0; } @@ -206,9 +227,9 @@ return -EBUSY; } } - - list_del_init(&dentry->d_hash); + __d_drop(dentry); spin_unlock(&dcache_lock); + return 0; } @@ -217,6 +238,7 @@ static inline struct dentry * __dget_locked(struct dentry *dentry) { atomic_inc(&dentry->d_count); + dentry->d_vfs_flags |= DCACHE_REFERENCED; if (atomic_read(&dentry->d_count) == 1) { dentry_stat.nr_unused--; list_del_init(&dentry->d_lru); @@ -254,7 +276,7 @@ tmp = next; next = tmp->next; alias = list_entry(tmp, struct dentry, d_alias); - if (!list_empty(&alias->d_hash)) { + if (!d_unhashed(alias)) { if (alias->d_flags & DCACHE_DISCONNECTED) discon_alias = alias; else { @@ -284,8 +306,8 @@ struct dentry *dentry = list_entry(tmp, struct dentry, d_alias); if (!atomic_read(&dentry->d_count)) { __dget_locked(dentry); + __d_drop(dentry); spin_unlock(&dcache_lock); - d_drop(dentry); dput(dentry); goto restart; } @@ -303,8 +325,9 @@ { struct dentry * parent; - list_del_init(&dentry->d_hash); + __d_drop(dentry); list_del(&dentry->d_child); + spin_unlock(&dentry->d_lock); dentry_iput(dentry); parent = dentry->d_parent; d_free(dentry); @@ -338,19 +361,20 @@ if (tmp == &dentry_unused) break; list_del_init(tmp); + dentry_stat.nr_unused--; dentry = list_entry(tmp, struct dentry, d_lru); - + + spin_lock(&dentry->d_lock); /* If the dentry was recently referenced, don't free it. */ if (dentry->d_vfs_flags & DCACHE_REFERENCED) { dentry->d_vfs_flags &= ~DCACHE_REFERENCED; - list_add(&dentry->d_lru, &dentry_unused); + if (!atomic_read(&dentry->d_count)) { + list_add(&dentry->d_lru, &dentry_unused); + dentry_stat.nr_unused++; + } + spin_unlock(&dentry->d_lock); continue; } - dentry_stat.nr_unused--; - - /* Unused dentry with a count? */ - if (atomic_read(&dentry->d_count)) - BUG(); prune_one_dentry(dentry); if (!--count) @@ -413,10 +437,13 @@ dentry = list_entry(tmp, struct dentry, d_lru); if (dentry->d_sb != sb) continue; - if (atomic_read(&dentry->d_count)) - continue; dentry_stat.nr_unused--; list_del_init(tmp); + spin_lock(&dentry->d_lock); + if (atomic_read(&dentry->d_count)) { + spin_unlock(&dentry->d_lock); + continue; + } prune_one_dentry(dentry); goto repeat; } @@ -496,8 +523,8 @@ struct list_head *tmp = next; struct dentry *dentry = list_entry(tmp, struct dentry, d_child); next = tmp->next; + list_del_init(&dentry->d_lru); if (!atomic_read(&dentry->d_count)) { - list_del(&dentry->d_lru); list_add(&dentry->d_lru, dentry_unused.prev); found++; } @@ -560,8 +587,8 @@ spin_lock(&dcache_lock); list_for_each(lp, head) { struct dentry *this = list_entry(lp, struct dentry, d_hash); + list_del(&this->d_lru); if (!atomic_read(&this->d_count)) { - list_del(&this->d_lru); list_add_tail(&this->d_lru, &dentry_unused); found++; } @@ -641,7 +668,8 @@ str[name->len] = 0; atomic_set(&dentry->d_count, 1); - dentry->d_vfs_flags = 0; + dentry->d_vfs_flags = DCACHE_UNHASHED; + dentry->d_lock = SPIN_LOCK_UNLOCKED; dentry->d_flags = 0; dentry->d_inode = NULL; dentry->d_parent = NULL; @@ -847,24 +875,14 @@ struct dentry * d_lookup(struct dentry * parent, struct qstr * name) { - struct dentry * dentry; - spin_lock(&dcache_lock); - dentry = __d_lookup(parent,name); - if (dentry) - __dget_locked(dentry); - spin_unlock(&dcache_lock); - return dentry; -} - -struct dentry * __d_lookup(struct dentry * parent, struct qstr * name) -{ - unsigned int len = name->len; unsigned int hash = name->hash; const unsigned char *str = name->name; struct list_head *head = d_hash(parent,hash); struct list_head *tmp; + struct dentry *found = NULL; + rcu_read_lock(); tmp = head->next; for (;;) { struct dentry * dentry = list_entry(tmp, struct dentry, d_hash); @@ -884,9 +902,14 @@ if (memcmp(dentry->d_name.name, str, len)) continue; } - return dentry; - } - return NULL; + spin_lock(&dentry->d_lock); + if (!d_unhashed(dentry)) + found = dget(dentry); + spin_unlock(&dentry->d_lock); + break; + } + rcu_read_unlock(); + return found; } /** @@ -925,7 +948,7 @@ lhp = base = d_hash(dparent, dentry->d_name.hash); while ((lhp = lhp->next) != base) { if (dentry == list_entry(lhp, struct dentry, d_hash)) { - __dget_locked(dentry); + dget(dentry); spin_unlock(&dcache_lock); return 1; } @@ -962,17 +985,18 @@ * Are we the only user? */ spin_lock(&dcache_lock); + spin_lock(&dentry->d_lock); if (atomic_read(&dentry->d_count) == 1) { + spin_unlock(&dentry->d_lock); dentry_iput(dentry); return; } - spin_unlock(&dcache_lock); - /* - * If not, just drop the dentry and let dput - * pick up the tab.. - */ - d_drop(dentry); + if (!d_unhashed(dentry)) + __d_drop(dentry); + + spin_unlock(&dentry->d_lock); + spin_unlock(&dcache_lock); } /** @@ -985,9 +1009,10 @@ void d_rehash(struct dentry * entry) { struct list_head *list = d_hash(entry->d_parent, entry->d_name.hash); - if (!list_empty(&entry->d_hash)) BUG(); spin_lock(&dcache_lock); + if (!list_empty(&entry->d_hash) && !d_unhashed(entry)) BUG(); list_add(&entry->d_hash, list); + entry->d_vfs_flags &= ~DCACHE_UNHASHED; spin_unlock(&dcache_lock); } @@ -1057,7 +1082,7 @@ list_add(&dentry->d_hash, &target->d_hash); /* Unhash the target: dput() will then get rid of it */ - list_del_init(&target->d_hash); + __d_drop(target); list_del(&dentry->d_child); list_del(&target->d_child); @@ -1109,7 +1134,7 @@ *--end = '\0'; buflen--; - if (!IS_ROOT(dentry) && list_empty(&dentry->d_hash)) { + if (!IS_ROOT(dentry) && d_unhashed(dentry)) { buflen -= 10; end -= 10; memcpy(end, " (deleted)", 10); @@ -1192,7 +1217,7 @@ error = -ENOENT; /* Has the current directory has been unlinked? */ spin_lock(&dcache_lock); - if (pwd->d_parent == pwd || !list_empty(&pwd->d_hash)) { + if (pwd->d_parent == pwd || !d_unhashed(pwd)) { unsigned long len; char * cwd; diff -urN linux-2.5.30-base/fs/driverfs/inode.c linux-2.5.30-dc12/fs/driverfs/inode.c --- linux-2.5.30-base/fs/driverfs/inode.c Fri Aug 2 02:46:08 2002 +++ linux-2.5.30-dc12/fs/driverfs/inode.c Fri Aug 2 17:05:52 2002 @@ -231,7 +231,7 @@ if (atomic_read(&dentry->d_count) != 2) break; case 2: - list_del_init(&dentry->d_hash); + __d_drop(dentry); } spin_unlock(&dcache_lock); } diff -urN linux-2.5.30-base/fs/intermezzo/journal.c linux-2.5.30-dc12/fs/intermezzo/journal.c --- linux-2.5.30-base/fs/intermezzo/journal.c Fri Aug 2 02:46:03 2002 +++ linux-2.5.30-dc12/fs/intermezzo/journal.c Fri Aug 2 17:03:18 2002 @@ -184,7 +184,7 @@ *--end = '\0'; buflen--; - if (dentry->d_parent != dentry && list_empty(&dentry->d_hash)) { + if (dentry->d_parent != dentry && d_unhashed(dentry)) { buflen -= 10; end -= 10; memcpy(end, " (deleted)", 10); diff -urN linux-2.5.30-base/fs/libfs.c linux-2.5.30-dc12/fs/libfs.c --- linux-2.5.30-base/fs/libfs.c Fri Aug 2 02:46:02 2002 +++ linux-2.5.30-dc12/fs/libfs.c Fri Aug 2 17:03:18 2002 @@ -70,7 +70,7 @@ while (n && p != &file->f_dentry->d_subdirs) { struct dentry *next; next = list_entry(p, struct dentry, d_child); - if (!list_empty(&next->d_hash) && next->d_inode) + if (!d_unhashed(next) && next->d_inode) n--; p = p->next; } @@ -127,7 +127,7 @@ for (p=q->next; p != &dentry->d_subdirs; p=p->next) { struct dentry *next; next = list_entry(p, struct dentry, d_child); - if (list_empty(&next->d_hash) || !next->d_inode) + if (d_unhashed(next) || !next->d_inode) continue; spin_unlock(&dcache_lock); diff -urN linux-2.5.30-base/fs/namei.c linux-2.5.30-dc12/fs/namei.c --- linux-2.5.30-base/fs/namei.c Fri Aug 2 02:46:18 2002 +++ linux-2.5.30-dc12/fs/namei.c Fri Aug 2 17:03:18 2002 @@ -286,27 +286,6 @@ return dentry; } -/*for fastwalking*/ -static inline void unlock_nd(struct nameidata *nd) -{ - struct vfsmount *mnt = nd->old_mnt; - struct dentry *dentry = nd->old_dentry; - mntget(nd->mnt); - dget_locked(nd->dentry); - nd->old_mnt = NULL; - nd->old_dentry = NULL; - spin_unlock(&dcache_lock); - dput(dentry); - mntput(mnt); -} - -static inline void lock_nd(struct nameidata *nd) -{ - spin_lock(&dcache_lock); - nd->old_mnt = nd->mnt; - nd->old_dentry = nd->dentry; -} - /* * Short-cut version of permission(), for calling by * path_walk(), when dcache lock is held. Combines parts @@ -451,11 +430,18 @@ { int res = 0; while (d_mountpoint(*dentry)) { - struct vfsmount *mounted = lookup_mnt(*mnt, *dentry); - if (!mounted) + struct vfsmount *mounted; + spin_lock(&dcache_lock); + mounted = lookup_mnt(*mnt, *dentry); + if (!mounted) { + spin_unlock(&dcache_lock); break; - *mnt = mounted; - *dentry = mounted->mnt_root; + } + *mnt = mntget(mounted); + spin_unlock(&dcache_lock); + dput(*dentry); + mntput(mounted->mnt_parent); + *dentry = dget(mounted->mnt_root); res = 1; } return res; @@ -488,17 +474,27 @@ { while(1) { struct vfsmount *parent; + struct dentry *old = *dentry; if (*dentry == current->fs->root && *mnt == current->fs->rootmnt) break; + spin_lock(&dcache_lock); if (*dentry != (*mnt)->mnt_root) { - *dentry = (*dentry)->d_parent; + *dentry = dget((*dentry)->d_parent); + spin_unlock(&dcache_lock); + dput(old); break; } - parent=(*mnt)->mnt_parent; - if (parent == *mnt) + parent = (*mnt)->mnt_parent; + if (parent == *mnt) { + spin_unlock(&dcache_lock); break; - *dentry=(*mnt)->mnt_mountpoint; + } + mntget(parent); + *dentry = dget((*mnt)->mnt_mountpoint); + spin_unlock(&dcache_lock); + dput(old); + mntput(*mnt); *mnt = parent; } follow_mount(mnt, dentry); @@ -515,14 +511,13 @@ * It _is_ time-critical. */ static int do_lookup(struct nameidata *nd, struct qstr *name, - struct path *path, struct path *cached_path, - int flags) + struct path *path, int flags) { struct vfsmount *mnt = nd->mnt; - struct dentry *dentry = __d_lookup(nd->dentry, name); + struct dentry *dentry = d_lookup(nd->dentry, name); if (!dentry) - goto dcache_miss; + goto need_lookup; if (dentry->d_op && dentry->d_op->d_revalidate) goto need_revalidate; done: @@ -530,36 +525,21 @@ path->dentry = dentry; return 0; -dcache_miss: - unlock_nd(nd); - need_lookup: dentry = real_lookup(nd->dentry, name, LOOKUP_CONTINUE); if (IS_ERR(dentry)) goto fail; - mntget(mnt); -relock: - dput(cached_path->dentry); - mntput(cached_path->mnt); - cached_path->mnt = mnt; - cached_path->dentry = dentry; - lock_nd(nd); goto done; need_revalidate: - mntget(mnt); - dget_locked(dentry); - unlock_nd(nd); if (dentry->d_op->d_revalidate(dentry, flags)) - goto relock; + goto done; if (d_invalidate(dentry)) - goto relock; + goto done; dput(dentry); - mntput(mnt); goto need_lookup; fail: - lock_nd(nd); return PTR_ERR(dentry); } @@ -573,7 +553,7 @@ */ int link_path_walk(const char * name, struct nameidata *nd) { - struct path next, pinned = {NULL, NULL}; + struct path next; struct inode *inode; int err; unsigned int lookup_flags = nd->flags; @@ -594,10 +574,8 @@ unsigned int c; err = exec_permission_lite(inode); - if (err == -EAGAIN) { - unlock_nd(nd); + if (err == -EAGAIN) { err = permission(inode, MAY_EXEC); - lock_nd(nd); } if (err) break; @@ -648,7 +626,7 @@ break; } /* This does the actual lookups.. */ - err = do_lookup(nd, &this, &next, &pinned, LOOKUP_CONTINUE); + err = do_lookup(nd, &this, &next, LOOKUP_CONTINUE); if (err) break; /* Check mountpoints.. */ @@ -657,21 +635,16 @@ err = -ENOENT; inode = next.dentry->d_inode; if (!inode) - break; + goto out_dput; err = -ENOTDIR; if (!inode->i_op) - break; + goto out_dput; if (inode->i_op->follow_link) { - mntget(next.mnt); - dget_locked(next.dentry); - unlock_nd(nd); err = do_follow_link(next.dentry, nd); dput(next.dentry); - mntput(next.mnt); if (err) goto return_err; - lock_nd(nd); err = -ENOENT; inode = nd->dentry->d_inode; if (!inode) @@ -680,6 +653,7 @@ if (!inode->i_op) break; } else { + dput(nd->dentry); nd->mnt = next.mnt; nd->dentry = next.dentry; } @@ -711,24 +685,20 @@ if (err < 0) break; } - err = do_lookup(nd, &this, &next, &pinned, 0); + err = do_lookup(nd, &this, &next, 0); if (err) break; follow_mount(&next.mnt, &next.dentry); inode = next.dentry->d_inode; if ((lookup_flags & LOOKUP_FOLLOW) && inode && inode->i_op && inode->i_op->follow_link) { - mntget(next.mnt); - dget_locked(next.dentry); - unlock_nd(nd); err = do_follow_link(next.dentry, nd); dput(next.dentry); - mntput(next.mnt); if (err) goto return_err; inode = nd->dentry->d_inode; - lock_nd(nd); } else { + dput(nd->dentry); nd->mnt = next.mnt; nd->dentry = next.dentry; } @@ -751,23 +721,19 @@ else if (this.len == 2 && this.name[1] == '.') nd->last_type = LAST_DOTDOT; return_base: - unlock_nd(nd); - dput(pinned.dentry); - mntput(pinned.mnt); return 0; +out_dput: + dput(next.dentry); + break; } - unlock_nd(nd); path_release(nd); return_err: - dput(pinned.dentry); - mntput(pinned.mnt); return err; } int path_walk(const char * name, struct nameidata *nd) { current->total_link_count = 0; - lock_nd(nd); return link_path_walk(name, nd); } @@ -855,8 +821,9 @@ { nd->last_type = LAST_ROOT; /* if there are only slashes... */ nd->flags = flags; + + read_lock(¤t->fs->lock); if (*name=='/') { - read_lock(¤t->fs->lock); if (current->fs->altroot && !(nd->flags & LOOKUP_NOALT)) { nd->mnt = mntget(current->fs->altrootmnt); nd->dentry = dget(current->fs->altroot); @@ -865,18 +832,14 @@ return 0; read_lock(¤t->fs->lock); } - read_unlock(¤t->fs->lock); - spin_lock(&dcache_lock); - nd->mnt = current->fs->rootmnt; - nd->dentry = current->fs->root; + nd->mnt = mntget(current->fs->rootmnt); + nd->dentry = dget(current->fs->root); } else{ - spin_lock(&dcache_lock); - nd->mnt = current->fs->pwdmnt; - nd->dentry = current->fs->pwd; + nd->mnt = mntget(current->fs->pwdmnt); + nd->dentry = dget(current->fs->pwd); } - nd->old_mnt = NULL; - nd->old_dentry = NULL; + read_unlock(¤t->fs->lock); current->total_link_count = 0; return link_path_walk(name, nd); } @@ -1548,7 +1511,7 @@ if (atomic_read(&dentry->d_count) != 2) break; case 2: - list_del_init(&dentry->d_hash); + __d_drop(dentry); } spin_unlock(&dcache_lock); } @@ -2115,7 +2078,6 @@ /* weird __emul_prefix() stuff did it */ goto out; } - lock_nd(nd); res = link_path_walk(link, nd); out: if (current->link_count || res || nd->last_type!=LAST_NORM) diff -urN linux-2.5.30-base/fs/nfs/dir.c linux-2.5.30-dc12/fs/nfs/dir.c --- linux-2.5.30-base/fs/nfs/dir.c Fri Aug 2 02:46:25 2002 +++ linux-2.5.30-dc12/fs/nfs/dir.c Fri Aug 2 17:05:38 2002 @@ -1002,7 +1002,7 @@ return error; } if (!d_unhashed(dentry)) { - list_del_init(&dentry->d_hash); + __d_drop(dentry); need_rehash = 1; } spin_unlock(&dcache_lock); diff -urN linux-2.5.30-base/include/linux/dcache.h linux-2.5.30-dc12/include/linux/dcache.h --- linux-2.5.30-base/include/linux/dcache.h Fri Aug 2 02:46:53 2002 +++ linux-2.5.30-dc12/include/linux/dcache.h Fri Aug 2 17:03:18 2002 @@ -7,6 +7,7 @@ #include <linux/mount.h> #include <linux/list.h> #include <linux/spinlock.h> +#include <linux/rcupdate.h> #include <asm/page.h> /* for BUG() */ /* @@ -68,11 +69,13 @@ struct dentry { atomic_t d_count; + unsigned long d_vfs_flags; /* moved here to be on same cacheline */ + spinlock_t d_lock; /* per dentry lock */ unsigned int d_flags; struct inode * d_inode; /* Where the name belongs to - NULL is negative */ struct dentry * d_parent; /* parent directory */ struct list_head d_hash; /* lookup hash list */ - struct list_head d_lru; /* d_count = 0 LRU list */ + struct list_head d_lru; /* LRU list */ struct list_head d_child; /* child of parent list */ struct list_head d_subdirs; /* our children */ struct list_head d_alias; /* inode alias list */ @@ -81,8 +84,8 @@ unsigned long d_time; /* used by d_revalidate */ struct dentry_operations *d_op; struct super_block * d_sb; /* The root of the dentry tree */ - unsigned long d_vfs_flags; void * d_fsdata; /* fs-specific data */ + struct rcu_head d_rcu; unsigned char d_iname[DNAME_INLINE_LEN]; /* small names */ }; @@ -132,6 +135,8 @@ */ #define DCACHE_REFERENCED 0x0008 /* Recently used, don't discard. */ +#define DCACHE_UNHASHED 0x0010 +#define DCACHE_FREEING 0x0020 extern spinlock_t dcache_lock; extern rwlock_t dparent_lock; @@ -153,11 +158,16 @@ * timeouts or autofs deletes). */ +static __inline__ void __d_drop(struct dentry * dentry) +{ + dentry->d_vfs_flags |= DCACHE_UNHASHED; + list_del_rcu(&dentry->d_hash); +} + static __inline__ void d_drop(struct dentry * dentry) { spin_lock(&dcache_lock); - list_del(&dentry->d_hash); - INIT_LIST_HEAD(&dentry->d_hash); + __d_drop(dentry); spin_unlock(&dcache_lock); } @@ -257,9 +267,8 @@ static __inline__ struct dentry * dget(struct dentry *dentry) { if (dentry) { - if (!atomic_read(&dentry->d_count)) - BUG(); atomic_inc(&dentry->d_count); + dentry->d_vfs_flags |= DCACHE_REFERENCED; } return dentry; } @@ -275,7 +284,7 @@ static __inline__ int d_unhashed(struct dentry *dentry) { - return list_empty(&dentry->d_hash); + return (dentry->d_vfs_flags & DCACHE_UNHASHED); } extern void dput(struct dentry *); diff -urN linux-2.5.30-base/include/linux/fs_struct.h linux-2.5.30-dc12/include/linux/fs_struct.h --- linux-2.5.30-base/include/linux/fs_struct.h Fri Aug 2 02:46:10 2002 +++ linux-2.5.30-dc12/include/linux/fs_struct.h Fri Aug 2 17:03:18 2002 @@ -35,12 +35,10 @@ struct dentry *old_root; struct vfsmount *old_rootmnt; write_lock(&fs->lock); - spin_lock(&dcache_lock); old_root = fs->root; old_rootmnt = fs->rootmnt; fs->rootmnt = mntget(mnt); fs->root = dget(dentry); - spin_unlock(&dcache_lock); write_unlock(&fs->lock); if (old_root) { dput(old_root); @@ -60,12 +58,10 @@ struct dentry *old_pwd; struct vfsmount *old_pwdmnt; write_lock(&fs->lock); - spin_lock(&dcache_lock); old_pwd = fs->pwd; old_pwdmnt = fs->pwdmnt; fs->pwdmnt = mntget(mnt); fs->pwd = dget(dentry); - spin_unlock(&dcache_lock); write_unlock(&fs->lock); if (old_pwd) { dput(old_pwd); diff -urN linux-2.5.30-base/kernel/exit.c linux-2.5.30-dc12/kernel/exit.c --- linux-2.5.30-base/kernel/exit.c Fri Aug 2 02:46:18 2002 +++ linux-2.5.30-dc12/kernel/exit.c Fri Aug 2 17:03:18 2002 @@ -40,9 +40,9 @@ proc_dentry = p->proc_dentry; if (unlikely(proc_dentry != NULL)) { spin_lock(&dcache_lock); - if (!list_empty(&proc_dentry->d_hash)) { + if (!d_unhashed(proc_dentry)) { dget_locked(proc_dentry); - list_del_init(&proc_dentry->d_hash); + __d_drop(proc_dentry); } else proc_dentry = NULL; spin_unlock(&dcache_lock); - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
