From b07ad9967f40b164af77205027352ba53729cf5a Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Sat, 23 Apr 2011 22:32:03 -0700 Subject: vfs: get rid of 'struct dcache_hash_bucket' abstraction It's a useless abstraction for 'hlist_bl_head', and it doesn't actually help anything - quite the reverse. All the users end up having to know about the hlist_bl_head details anyway, using 'struct hlist_bl_node *' etc. So it just makes the code look confusing. And the cost of it is extra '&b->head' syntactic noise, but more importantly it spuriously makes the hash table dentry list look different from the per-superblock DCACHE_DISCONNECTED dentry list. As a result, the code ended up using ad-hoc locking for one case and special helper functions for what is really another totally identical case in the very same function. Make it all look and work the same. Signed-off-by: Linus Torvalds --- fs/dcache.c | 45 +++++++++++++++++++++------------------------ 1 file changed, 21 insertions(+), 24 deletions(-) (limited to 'fs/dcache.c') diff --git a/fs/dcache.c b/fs/dcache.c index 129a35730994..7108c15685dd 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -99,12 +99,9 @@ static struct kmem_cache *dentry_cache __read_mostly; static unsigned int d_hash_mask __read_mostly; static unsigned int d_hash_shift __read_mostly; -struct dcache_hash_bucket { - struct hlist_bl_head head; -}; -static struct dcache_hash_bucket *dentry_hashtable __read_mostly; +static struct hlist_bl_head *dentry_hashtable __read_mostly; -static inline struct dcache_hash_bucket *d_hash(struct dentry *parent, +static inline struct hlist_bl_head *d_hash(struct dentry *parent, unsigned long hash) { hash += ((unsigned long) parent ^ GOLDEN_RATIO_PRIME) / L1_CACHE_BYTES; @@ -112,14 +109,14 @@ static inline struct dcache_hash_bucket *d_hash(struct dentry *parent, return dentry_hashtable + (hash & D_HASHMASK); } -static inline void spin_lock_bucket(struct dcache_hash_bucket *b) +static inline void spin_lock_bucket(struct hlist_bl_head *b) { - bit_spin_lock(0, (unsigned long *)&b->head.first); + bit_spin_lock(0, (unsigned long *)&b->first); } -static inline void spin_unlock_bucket(struct dcache_hash_bucket *b) +static inline void spin_unlock_bucket(struct hlist_bl_head *b) { - __bit_spin_unlock(0, (unsigned long *)&b->head.first); + __bit_spin_unlock(0, (unsigned long *)&b->first); } /* Statistics gathering. */ @@ -331,15 +328,15 @@ static struct dentry *d_kill(struct dentry *dentry, struct dentry *parent) void __d_drop(struct dentry *dentry) { if (!(dentry->d_flags & DCACHE_UNHASHED)) { + struct hlist_bl_head *b; if (unlikely(dentry->d_flags & DCACHE_DISCONNECTED)) { - bit_spin_lock(0, - (unsigned long *)&dentry->d_sb->s_anon.first); + b = &dentry->d_sb->s_anon; + spin_lock_bucket(b); dentry->d_flags |= DCACHE_UNHASHED; hlist_bl_del_init(&dentry->d_hash); - __bit_spin_unlock(0, - (unsigned long *)&dentry->d_sb->s_anon.first); + spin_unlock_bucket(b); } else { - struct dcache_hash_bucket *b; + struct hlist_bl_head *b; b = d_hash(dentry->d_parent, dentry->d_name.hash); spin_lock_bucket(b); /* @@ -1789,7 +1786,7 @@ struct dentry *__d_lookup_rcu(struct dentry *parent, struct qstr *name, unsigned int len = name->len; unsigned int hash = name->hash; const unsigned char *str = name->name; - struct dcache_hash_bucket *b = d_hash(parent, hash); + struct hlist_bl_head *b = d_hash(parent, hash); struct hlist_bl_node *node; struct dentry *dentry; @@ -1813,7 +1810,7 @@ struct dentry *__d_lookup_rcu(struct dentry *parent, struct qstr *name, * * See Documentation/filesystems/path-lookup.txt for more details. */ - hlist_bl_for_each_entry_rcu(dentry, node, &b->head, d_hash) { + hlist_bl_for_each_entry_rcu(dentry, node, b, d_hash) { struct inode *i; const char *tname; int tlen; @@ -1908,7 +1905,7 @@ 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 dcache_hash_bucket *b = d_hash(parent, hash); + struct hlist_bl_head *b = d_hash(parent, hash); struct hlist_bl_node *node; struct dentry *found = NULL; struct dentry *dentry; @@ -1935,7 +1932,7 @@ struct dentry *__d_lookup(struct dentry *parent, struct qstr *name) */ rcu_read_lock(); - hlist_bl_for_each_entry_rcu(dentry, node, &b->head, d_hash) { + hlist_bl_for_each_entry_rcu(dentry, node, b, d_hash) { const char *tname; int tlen; @@ -2086,12 +2083,12 @@ again: } EXPORT_SYMBOL(d_delete); -static void __d_rehash(struct dentry * entry, struct dcache_hash_bucket *b) +static void __d_rehash(struct dentry * entry, struct hlist_bl_head *b) { BUG_ON(!d_unhashed(entry)); spin_lock_bucket(b); entry->d_flags &= ~DCACHE_UNHASHED; - hlist_bl_add_head_rcu(&entry->d_hash, &b->head); + hlist_bl_add_head_rcu(&entry->d_hash, b); spin_unlock_bucket(b); } @@ -3025,7 +3022,7 @@ static void __init dcache_init_early(void) dentry_hashtable = alloc_large_system_hash("Dentry cache", - sizeof(struct dcache_hash_bucket), + sizeof(struct hlist_bl_head), dhash_entries, 13, HASH_EARLY, @@ -3034,7 +3031,7 @@ static void __init dcache_init_early(void) 0); for (loop = 0; loop < (1 << d_hash_shift); loop++) - INIT_HLIST_BL_HEAD(&dentry_hashtable[loop].head); + INIT_HLIST_BL_HEAD(dentry_hashtable + loop); } static void __init dcache_init(void) @@ -3057,7 +3054,7 @@ static void __init dcache_init(void) dentry_hashtable = alloc_large_system_hash("Dentry cache", - sizeof(struct dcache_hash_bucket), + sizeof(struct hlist_bl_head), dhash_entries, 13, 0, @@ -3066,7 +3063,7 @@ static void __init dcache_init(void) 0); for (loop = 0; loop < (1 << d_hash_shift); loop++) - INIT_HLIST_BL_HEAD(&dentry_hashtable[loop].head); + INIT_HLIST_BL_HEAD(dentry_hashtable + loop); } /* SLAB cache for __getname() consumers */ -- cgit v1.2.3 From dea3667bc3c2a0521e8d8855e407a49d9d70028c Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Sun, 24 Apr 2011 07:58:46 -0700 Subject: vfs: get rid of insane dentry hashing rules The dentry hashing rules have been really quite complicated for a long while, in odd ways. That made functions like __d_drop() very fragile and non-obvious. In particular, whether a dentry was hashed or not was indicated with an explicit DCACHE_UNHASHED bit. That's despite the fact that the hash abstraction that the dentries use actually have a 'is this entry hashed or not' model (which is a simple test of the 'pprev' pointer). The reason that was done is because we used the normal 'is this entry unhashed' model to mark whether the dentry had _ever_ been hashed in the dentry hash tables, and that logic goes back many years (commit b3423415fbc2: "dcache: avoid RCU for never-hashed dentries"). That, in turn, meant that __d_drop had totally different unhashing logic for the dentry hash table case and for the anonymous dcache case, because in order to use the "is this dentry hashed" logic as a flag for whether it had ever been on the RCU hash table, we had to unhash such a dentry differently so that we'd never think that it wasn't 'unhashed' and wouldn't be free'd correctly. That's just insane. It made the logic really hard to follow, when there were two different kinds of "unhashed" states, and one of them (the one that used "list_bl_unhashed()") really had nothing at all to do with being unhashed per se, but with a very subtle lifetime rule instead. So turn all of it around, and make it logical. Instead of having a DENTRY_UNHASHED bit in d_flags to indicate whether the dentry is on the hash chains or not, use the hash chain unhashed logic for that. Suddenly "d_unhashed()" just uses "list_bl_unhashed()", and everything makes sense. And for the lifetime rule, just use an explicit DENTRY_RCUACCEES bit. If we ever insert the dentry into the dentry hash table so that it is visible to RCU lookup, we mark it DENTRY_RCUACCESS to show that it now needs the RCU lifetime rules. Now suddently that test at dentry free time makes sense too. And because unhashing now is sane and doesn't depend on where the dentry got unhashed from (because the dentry hash chain details doesn't have some subtle side effects), we can re-unify the __d_drop() logic and use common code for the unhashing. Also fix one more open-coded hash chain bit_spin_lock() that I missed in the previous chain locking cleanup commit. Signed-off-by: Linus Torvalds --- fs/dcache.c | 42 ++++++++++++++++-------------------------- 1 file changed, 16 insertions(+), 26 deletions(-) (limited to 'fs/dcache.c') diff --git a/fs/dcache.c b/fs/dcache.c index 7108c15685dd..d600a0af3b2e 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -164,8 +164,8 @@ static void d_free(struct dentry *dentry) if (dentry->d_op && dentry->d_op->d_release) dentry->d_op->d_release(dentry); - /* if dentry was never inserted into hash, immediate free is OK */ - if (hlist_bl_unhashed(&dentry->d_hash)) + /* if dentry was never visible to RCU, immediate free is OK */ + if (!(dentry->d_flags & DCACHE_RCUACCESS)) __d_free(&dentry->d_u.d_rcu); else call_rcu(&dentry->d_u.d_rcu, __d_free); @@ -327,28 +327,19 @@ static struct dentry *d_kill(struct dentry *dentry, struct dentry *parent) */ void __d_drop(struct dentry *dentry) { - if (!(dentry->d_flags & DCACHE_UNHASHED)) { + if (!d_unhashed(dentry)) { struct hlist_bl_head *b; - if (unlikely(dentry->d_flags & DCACHE_DISCONNECTED)) { + if (unlikely(dentry->d_flags & DCACHE_DISCONNECTED)) b = &dentry->d_sb->s_anon; - spin_lock_bucket(b); - dentry->d_flags |= DCACHE_UNHASHED; - hlist_bl_del_init(&dentry->d_hash); - spin_unlock_bucket(b); - } else { - struct hlist_bl_head *b; + else b = d_hash(dentry->d_parent, dentry->d_name.hash); - spin_lock_bucket(b); - /* - * We may not actually need to put DCACHE_UNHASHED - * manipulations under the hash lock, but follow - * the principle of least surprise. - */ - dentry->d_flags |= DCACHE_UNHASHED; - hlist_bl_del_rcu(&dentry->d_hash); - spin_unlock_bucket(b); - dentry_rcuwalk_barrier(dentry); - } + + spin_lock_bucket(b); + __hlist_bl_del(&dentry->d_hash); + dentry->d_hash.pprev = NULL; + spin_unlock_bucket(b); + + dentry_rcuwalk_barrier(dentry); } } EXPORT_SYMBOL(__d_drop); @@ -1301,7 +1292,7 @@ struct dentry *d_alloc(struct dentry * parent, const struct qstr *name) dname[name->len] = 0; dentry->d_count = 1; - dentry->d_flags = DCACHE_UNHASHED; + dentry->d_flags = 0; spin_lock_init(&dentry->d_lock); seqcount_init(&dentry->d_seq); dentry->d_inode = NULL; @@ -1603,10 +1594,9 @@ struct dentry *d_obtain_alias(struct inode *inode) tmp->d_inode = inode; tmp->d_flags |= DCACHE_DISCONNECTED; list_add(&tmp->d_alias, &inode->i_dentry); - bit_spin_lock(0, (unsigned long *)&tmp->d_sb->s_anon.first); - tmp->d_flags &= ~DCACHE_UNHASHED; + spin_lock_bucket(&tmp->d_sb->s_anon); hlist_bl_add_head(&tmp->d_hash, &tmp->d_sb->s_anon); - __bit_spin_unlock(0, (unsigned long *)&tmp->d_sb->s_anon.first); + spin_unlock_bucket(&tmp->d_sb->s_anon); spin_unlock(&tmp->d_lock); spin_unlock(&inode->i_lock); security_d_instantiate(tmp, inode); @@ -2087,7 +2077,7 @@ static void __d_rehash(struct dentry * entry, struct hlist_bl_head *b) { BUG_ON(!d_unhashed(entry)); spin_lock_bucket(b); - entry->d_flags &= ~DCACHE_UNHASHED; + entry->d_flags |= DCACHE_RCUACCESS; hlist_bl_add_head_rcu(&entry->d_hash, b); spin_unlock_bucket(b); } -- cgit v1.2.3 From 1879fd6a26571fd4e8e1f4bb3e7537bc936b1fe7 Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Mon, 25 Apr 2011 14:01:36 -0400 Subject: add hlist_bl_lock/unlock helpers Now that the whole dcache_hash_bucket crap is gone, go all the way and also remove the weird locking layering violations for locking the hash buckets. Add hlist_bl_lock/unlock helpers to move the locking into the list abstraction instead of requiring each caller to open code it. After all allowing for the bit locks is the whole point of these helpers over the plain hlist variant. Signed-off-by: Christoph Hellwig Signed-off-by: Linus Torvalds --- fs/dcache.c | 22 ++++++---------------- 1 file changed, 6 insertions(+), 16 deletions(-) (limited to 'fs/dcache.c') diff --git a/fs/dcache.c b/fs/dcache.c index d600a0af3b2e..22a0ef41bad1 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -109,16 +109,6 @@ static inline struct hlist_bl_head *d_hash(struct dentry *parent, return dentry_hashtable + (hash & D_HASHMASK); } -static inline void spin_lock_bucket(struct hlist_bl_head *b) -{ - bit_spin_lock(0, (unsigned long *)&b->first); -} - -static inline void spin_unlock_bucket(struct hlist_bl_head *b) -{ - __bit_spin_unlock(0, (unsigned long *)&b->first); -} - /* Statistics gathering. */ struct dentry_stat_t dentry_stat = { .age_limit = 45, @@ -334,10 +324,10 @@ void __d_drop(struct dentry *dentry) else b = d_hash(dentry->d_parent, dentry->d_name.hash); - spin_lock_bucket(b); + hlist_bl_lock(b); __hlist_bl_del(&dentry->d_hash); dentry->d_hash.pprev = NULL; - spin_unlock_bucket(b); + hlist_bl_unlock(b); dentry_rcuwalk_barrier(dentry); } @@ -1594,9 +1584,9 @@ struct dentry *d_obtain_alias(struct inode *inode) tmp->d_inode = inode; tmp->d_flags |= DCACHE_DISCONNECTED; list_add(&tmp->d_alias, &inode->i_dentry); - spin_lock_bucket(&tmp->d_sb->s_anon); + hlist_bl_lock(&tmp->d_sb->s_anon); hlist_bl_add_head(&tmp->d_hash, &tmp->d_sb->s_anon); - spin_unlock_bucket(&tmp->d_sb->s_anon); + hlist_bl_unlock(&tmp->d_sb->s_anon); spin_unlock(&tmp->d_lock); spin_unlock(&inode->i_lock); security_d_instantiate(tmp, inode); @@ -2076,10 +2066,10 @@ EXPORT_SYMBOL(d_delete); static void __d_rehash(struct dentry * entry, struct hlist_bl_head *b) { BUG_ON(!d_unhashed(entry)); - spin_lock_bucket(b); + hlist_bl_lock(b); entry->d_flags |= DCACHE_RCUACCESS; hlist_bl_add_head_rcu(&entry->d_hash, b); - spin_unlock_bucket(b); + hlist_bl_unlock(b); } static void _d_rehash(struct dentry * entry) -- cgit v1.2.3 From 268bb0ce3e87872cb9290c322b0d35bce230d88f Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Fri, 20 May 2011 12:50:29 -0700 Subject: sanitize usage Commit e66eed651fd1 ("list: remove prefetching from regular list iterators") removed the include of prefetch.h from list.h, which uncovered several cases that had apparently relied on that rather obscure header file dependency. So this fixes things up a bit, using grep -L linux/prefetch.h $(git grep -l '[^a-z_]prefetchw*(' -- '*.[ch]') grep -L 'prefetchw*(' $(git grep -l 'linux/prefetch.h' -- '*.[ch]') to guide us in finding files that either need inclusion, or have it despite not needing it. There are more of them around (mostly network drivers), but this gets many core ones. Reported-by: Stephen Rothwell Signed-off-by: Linus Torvalds --- fs/dcache.c | 1 + 1 file changed, 1 insertion(+) (limited to 'fs/dcache.c') diff --git a/fs/dcache.c b/fs/dcache.c index 22a0ef41bad1..18b2a1f10ed8 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -35,6 +35,7 @@ #include #include #include +#include #include "internal.h" /* -- cgit v1.2.3 From 1495f230fa7750479c79e3656286b9183d662077 Mon Sep 17 00:00:00 2001 From: Ying Han Date: Tue, 24 May 2011 17:12:27 -0700 Subject: vmscan: change shrinker API by passing shrink_control struct Change each shrinker's API by consolidating the existing parameters into shrink_control struct. This will simplify any further features added w/o touching each file of shrinker. [akpm@linux-foundation.org: fix build] [akpm@linux-foundation.org: fix warning] [kosaki.motohiro@jp.fujitsu.com: fix up new shrinker API] [akpm@linux-foundation.org: fix xfs warning] [akpm@linux-foundation.org: update gfs2] Signed-off-by: Ying Han Cc: KOSAKI Motohiro Cc: Minchan Kim Acked-by: Pavel Emelyanov Cc: KAMEZAWA Hiroyuki Cc: Mel Gorman Acked-by: Rik van Riel Cc: Johannes Weiner Cc: Hugh Dickins Cc: Dave Hansen Cc: Steven Whitehouse Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/dcache.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) (limited to 'fs/dcache.c') diff --git a/fs/dcache.c b/fs/dcache.c index 18b2a1f10ed8..37f72ee5bf7c 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -1220,7 +1220,7 @@ void shrink_dcache_parent(struct dentry * parent) EXPORT_SYMBOL(shrink_dcache_parent); /* - * Scan `nr' dentries and return the number which remain. + * Scan `sc->nr_slab_to_reclaim' dentries and return the number which remain. * * We need to avoid reentering the filesystem if the caller is performing a * GFP_NOFS allocation attempt. One example deadlock is: @@ -1231,8 +1231,12 @@ EXPORT_SYMBOL(shrink_dcache_parent); * * In this case we return -1 to tell the caller that we baled. */ -static int shrink_dcache_memory(struct shrinker *shrink, int nr, gfp_t gfp_mask) +static int shrink_dcache_memory(struct shrinker *shrink, + struct shrink_control *sc) { + int nr = sc->nr_to_scan; + gfp_t gfp_mask = sc->gfp_mask; + if (nr) { if (!(gfp_mask & __GFP_FS)) return -1; -- cgit v1.2.3