inode: convert inode_sb_list_lock to per-sb

The process of reducing contention on per-superblock inode lists
starts with moving the locking to match the per-superblock inode
list. This takes the global lock out of the picture and reduces the
contention problems to within a single filesystem. This doesn't get
rid of contention as the locks still have global CPU scope, but it
does isolate operations on different superblocks form each other.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Josef Bacik <jbacik@fb.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Tested-by: Dave Chinner <dchinner@redhat.com>

diff --git a/fs/block_dev.c b/fs/block_dev.c
index 198243717da567bd5f47ad7c94ab823a82506c62..33b813e04f7921e390c9f4edec0908d4fcb9337f 100644 (file)
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -1769,7 +1769,7 @@ void iterate_bdevs(void (*func)(struct block_device *, void *), void *arg)
 {
        struct inode *inode, *old_inode = NULL;
 
-       spin_lock(&inode_sb_list_lock);
+       spin_lock(&blockdev_superblock->s_inode_list_lock);
        list_for_each_entry(inode, &blockdev_superblock->s_inodes, i_sb_list) {
                struct address_space *mapping = inode->i_mapping;
 
@@ -1781,13 +1781,13 @@ void iterate_bdevs(void (*func)(struct block_device *, void *), void *arg)
                }
                __iget(inode);
                spin_unlock(&inode->i_lock);
-               spin_unlock(&inode_sb_list_lock);
+               spin_unlock(&blockdev_superblock->s_inode_list_lock);
                /*
                 * We hold a reference to 'inode' so it couldn't have been
                 * removed from s_inodes list while we dropped the
-                * inode_sb_list_lock.  We cannot iput the inode now as we can
+                * s_inode_list_lock  We cannot iput the inode now as we can
                 * be holding the last reference and we cannot iput it under
-                * inode_sb_list_lock. So we keep the reference and iput it
+                * s_inode_list_lock. So we keep the reference and iput it
                 * later.
                 */
                iput(old_inode);
@@ -1795,8 +1795,8 @@ void iterate_bdevs(void (*func)(struct block_device *, void *), void *arg)
 
                func(I_BDEV(inode), arg);
 
-               spin_lock(&inode_sb_list_lock);
+               spin_lock(&blockdev_superblock->s_inode_list_lock);
        }
-       spin_unlock(&inode_sb_list_lock);
+       spin_unlock(&blockdev_superblock->s_inode_list_lock);
        iput(old_inode);
 }

diff --git a/fs/drop_caches.c b/fs/drop_caches.c
index 5718cb9f7273e83a2fe6c7775dcf76c636dd908a..d72d52b904333767328235a2de720107503cdcf2 100644 (file)
--- a/fs/drop_caches.c
+++ b/fs/drop_caches.c
@@ -17,7 +17,7 @@ static void drop_pagecache_sb(struct super_block *sb, void *unused)
 {
        struct inode *inode, *toput_inode = NULL;
 
-       spin_lock(&inode_sb_list_lock);
+       spin_lock(&sb->s_inode_list_lock);
        list_for_each_entry(inode, &sb->s_inodes, i_sb_list) {
                spin_lock(&inode->i_lock);
                if ((inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW)) ||
@@ -27,13 +27,15 @@ static void drop_pagecache_sb(struct super_block *sb, void *unused)
                }
                __iget(inode);
                spin_unlock(&inode->i_lock);
-               spin_unlock(&inode_sb_list_lock);
+               spin_unlock(&sb->s_inode_list_lock);
+
                invalidate_mapping_pages(inode->i_mapping, 0, -1);
                iput(toput_inode);
                toput_inode = inode;
-               spin_lock(&inode_sb_list_lock);
+
+               spin_lock(&sb->s_inode_list_lock);
        }
-       spin_unlock(&inode_sb_list_lock);
+       spin_unlock(&sb->s_inode_list_lock);
        iput(toput_inode);
 }
 

diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index d98e37bbf41799810b4ca28803636b259941ca7a..f45bf876579f39a0db10a154da1dd428c28a1cf5 100644 (file)
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -2124,7 +2124,7 @@ static void wait_sb_inodes(struct super_block *sb)
         */
        WARN_ON(!rwsem_is_locked(&sb->s_umount));
 
-       spin_lock(&inode_sb_list_lock);
+       spin_lock(&sb->s_inode_list_lock);
 
        /*
         * Data integrity sync. Must wait for all pages under writeback,
@@ -2144,14 +2144,14 @@ static void wait_sb_inodes(struct super_block *sb)
                }
                __iget(inode);
                spin_unlock(&inode->i_lock);
-               spin_unlock(&inode_sb_list_lock);
+               spin_unlock(&sb->s_inode_list_lock);
 
                /*
                 * We hold a reference to 'inode' so it couldn't have been
                 * removed from s_inodes list while we dropped the
-                * inode_sb_list_lock.  We cannot iput the inode now as we can
+                * s_inode_list_lock.  We cannot iput the inode now as we can
                 * be holding the last reference and we cannot iput it under
-                * inode_sb_list_lock. So we keep the reference and iput it
+                * s_inode_list_lock. So we keep the reference and iput it
                 * later.
                 */
                iput(old_inode);
@@ -2161,9 +2161,9 @@ static void wait_sb_inodes(struct super_block *sb)
 
                cond_resched();
 
-               spin_lock(&inode_sb_list_lock);
+               spin_lock(&sb->s_inode_list_lock);
        }
-       spin_unlock(&inode_sb_list_lock);
+       spin_unlock(&sb->s_inode_list_lock);
        iput(old_inode);
 }
 

diff --git a/fs/inode.c b/fs/inode.c
index d30640f7a193879d07f4ff2c12efe3b817a386f3..a2de294f6b77fcfade161dafc9e16fb59d5ff4d3 100644 (file)
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -28,8 +28,8 @@
  *   inode->i_state, inode->i_hash, __iget()
  * Inode LRU list locks protect:
  *   inode->i_sb->s_inode_lru, inode->i_lru
- * inode_sb_list_lock protects:
- *   sb->s_inodes, inode->i_sb_list
+ * inode->i_sb->s_inode_list_lock protects:
+ *   inode->i_sb->s_inodes, inode->i_sb_list
  * bdi->wb.list_lock protects:
  *   bdi->wb.b_{dirty,io,more_io,dirty_time}, inode->i_wb_list
  * inode_hash_lock protects:
@@ -37,7 +37,7 @@
  *
  * Lock ordering:
  *
- * inode_sb_list_lock
+ * inode->i_sb->s_inode_list_lock
  *   inode->i_lock
  *     Inode LRU list locks
  *
@@ -45,7 +45,7 @@
  *   inode->i_lock
  *
  * inode_hash_lock
- *   inode_sb_list_lock
+ *   inode->i_sb->s_inode_list_lock
  *   inode->i_lock
  *
  * iunique_lock
@@ -57,8 +57,6 @@ static unsigned int i_hash_shift __read_mostly;
 static struct hlist_head *inode_hashtable __read_mostly;
 static __cacheline_aligned_in_smp DEFINE_SPINLOCK(inode_hash_lock);
 
-__cacheline_aligned_in_smp DEFINE_SPINLOCK(inode_sb_list_lock);
-
 /*
  * Empty aops. Can be used for the cases where the user does not
  * define any of the address_space operations.
@@ -426,18 +424,18 @@ static void inode_lru_list_del(struct inode *inode)
  */
 void inode_sb_list_add(struct inode *inode)
 {
-       spin_lock(&inode_sb_list_lock);
+       spin_lock(&inode->i_sb->s_inode_list_lock);
        list_add(&inode->i_sb_list, &inode->i_sb->s_inodes);
-       spin_unlock(&inode_sb_list_lock);
+       spin_unlock(&inode->i_sb->s_inode_list_lock);
 }
 EXPORT_SYMBOL_GPL(inode_sb_list_add);
 
 static inline void inode_sb_list_del(struct inode *inode)
 {
        if (!list_empty(&inode->i_sb_list)) {
-               spin_lock(&inode_sb_list_lock);
+               spin_lock(&inode->i_sb->s_inode_list_lock);
                list_del_init(&inode->i_sb_list);
-               spin_unlock(&inode_sb_list_lock);
+               spin_unlock(&inode->i_sb->s_inode_list_lock);
        }
 }
 
@@ -594,7 +592,7 @@ void evict_inodes(struct super_block *sb)
        struct inode *inode, *next;
        LIST_HEAD(dispose);
 
-       spin_lock(&inode_sb_list_lock);
+       spin_lock(&sb->s_inode_list_lock);
        list_for_each_entry_safe(inode, next, &sb->s_inodes, i_sb_list) {
                if (atomic_read(&inode->i_count))
                        continue;
@@ -610,7 +608,7 @@ void evict_inodes(struct super_block *sb)
                spin_unlock(&inode->i_lock);
                list_add(&inode->i_lru, &dispose);
        }
-       spin_unlock(&inode_sb_list_lock);
+       spin_unlock(&sb->s_inode_list_lock);
 
        dispose_list(&dispose);
 }
@@ -631,7 +629,7 @@ int invalidate_inodes(struct super_block *sb, bool kill_dirty)
        struct inode *inode, *next;
        LIST_HEAD(dispose);
 
-       spin_lock(&inode_sb_list_lock);
+       spin_lock(&sb->s_inode_list_lock);
        list_for_each_entry_safe(inode, next, &sb->s_inodes, i_sb_list) {
                spin_lock(&inode->i_lock);
                if (inode->i_state & (I_NEW | I_FREEING | I_WILL_FREE)) {
@@ -654,7 +652,7 @@ int invalidate_inodes(struct super_block *sb, bool kill_dirty)
                spin_unlock(&inode->i_lock);
                list_add(&inode->i_lru, &dispose);
        }
-       spin_unlock(&inode_sb_list_lock);
+       spin_unlock(&sb->s_inode_list_lock);
 
        dispose_list(&dispose);
 
@@ -890,7 +888,7 @@ struct inode *new_inode(struct super_block *sb)
 {
        struct inode *inode;
 
-       spin_lock_prefetch(&inode_sb_list_lock);
+       spin_lock_prefetch(&sb->s_inode_list_lock);
 
        inode = new_inode_pseudo(sb);
        if (inode)

diff --git a/fs/internal.h b/fs/internal.h
index 4d5af583ab031964f5fd427953940e26ec671a78..ee1209c54eb1ee99022984621bcafd43fcdec252 100644 (file)
--- a/fs/internal.h
+++ b/fs/internal.h
@@ -112,7 +112,6 @@ extern int vfs_open(const struct path *, struct file *, const struct cred *);
 /*
  * inode.c
  */
-extern spinlock_t inode_sb_list_lock;
 extern long prune_icache_sb(struct super_block *sb, struct shrink_control *sc);
 extern void inode_add_lru(struct inode *inode);
 

diff --git a/fs/notify/inode_mark.c b/fs/notify/inode_mark.c
index 3daf513ee99e6ccf21ce01bfed71f85a21b5717e..a4e1a8f6c329e42e10d705864bb0e75c09212265 100644 (file)
--- a/fs/notify/inode_mark.c
+++ b/fs/notify/inode_mark.c
@@ -163,17 +163,17 @@ int fsnotify_add_inode_mark(struct fsnotify_mark *mark,
 
 /**
  * fsnotify_unmount_inodes - an sb is unmounting.  handle any watched inodes.
- * @list: list of inodes being unmounted (sb->s_inodes)
+ * @sb: superblock being unmounted.
  *
  * Called during unmount with no locks held, so needs to be safe against
- * concurrent modifiers. We temporarily drop inode_sb_list_lock and CAN block.
+ * concurrent modifiers. We temporarily drop sb->s_inode_list_lock and CAN block.
  */
-void fsnotify_unmount_inodes(struct list_head *list)
+void fsnotify_unmount_inodes(struct super_block *sb)
 {
        struct inode *inode, *next_i, *need_iput = NULL;
 
-       spin_lock(&inode_sb_list_lock);
-       list_for_each_entry_safe(inode, next_i, list, i_sb_list) {
+       spin_lock(&sb->s_inode_list_lock);
+       list_for_each_entry_safe(inode, next_i, &sb->s_inodes, i_sb_list) {
                struct inode *need_iput_tmp;
 
                /*
@@ -209,7 +209,7 @@ void fsnotify_unmount_inodes(struct list_head *list)
                spin_unlock(&inode->i_lock);
 
                /* In case the dropping of a reference would nuke next_i. */
-               while (&next_i->i_sb_list != list) {
+               while (&next_i->i_sb_list != &sb->s_inodes) {
                        spin_lock(&next_i->i_lock);
                        if (!(next_i->i_state & (I_FREEING | I_WILL_FREE)) &&
                                                atomic_read(&next_i->i_count)) {
@@ -224,12 +224,12 @@ void fsnotify_unmount_inodes(struct list_head *list)
                }
 
                /*
-                * We can safely drop inode_sb_list_lock here because either
+                * We can safely drop s_inode_list_lock here because either
                 * we actually hold references on both inode and next_i or
                 * end of list.  Also no new inodes will be added since the
                 * umount has begun.
                 */
-               spin_unlock(&inode_sb_list_lock);
+               spin_unlock(&sb->s_inode_list_lock);
 
                if (need_iput_tmp)
                        iput(need_iput_tmp);
@@ -241,7 +241,7 @@ void fsnotify_unmount_inodes(struct list_head *list)
 
                iput(inode);
 
-               spin_lock(&inode_sb_list_lock);
+               spin_lock(&sb->s_inode_list_lock);
        }
-       spin_unlock(&inode_sb_list_lock);
+       spin_unlock(&sb->s_inode_list_lock);
 }

diff --git a/fs/quota/dquot.c b/fs/quota/dquot.c
index 20d1f74561cf1354b6c5c2d5dabcb8052cf14a73..2863ec6cbadf384464c6ffee73e1b57c1285e561 100644 (file)
--- a/fs/quota/dquot.c
+++ b/fs/quota/dquot.c
@@ -923,7 +923,7 @@ static void add_dquot_ref(struct super_block *sb, int type)
        int reserved = 0;
 #endif
 
-       spin_lock(&inode_sb_list_lock);
+       spin_lock(&sb->s_inode_list_lock);
        list_for_each_entry(inode, &sb->s_inodes, i_sb_list) {
                spin_lock(&inode->i_lock);
                if ((inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW)) ||
@@ -934,7 +934,7 @@ static void add_dquot_ref(struct super_block *sb, int type)
                }
                __iget(inode);
                spin_unlock(&inode->i_lock);
-               spin_unlock(&inode_sb_list_lock);
+               spin_unlock(&sb->s_inode_list_lock);
 
 #ifdef CONFIG_QUOTA_DEBUG
                if (unlikely(inode_get_rsv_space(inode) > 0))
@@ -946,15 +946,15 @@ static void add_dquot_ref(struct super_block *sb, int type)
                /*
                 * We hold a reference to 'inode' so it couldn't have been
                 * removed from s_inodes list while we dropped the
-                * inode_sb_list_lock We cannot iput the inode now as we can be
+                * s_inode_list_lock. We cannot iput the inode now as we can be
                 * holding the last reference and we cannot iput it under
-                * inode_sb_list_lock. So we keep the reference and iput it
+                * s_inode_list_lock. So we keep the reference and iput it
                 * later.
                 */
                old_inode = inode;
-               spin_lock(&inode_sb_list_lock);
+               spin_lock(&sb->s_inode_list_lock);
        }
-       spin_unlock(&inode_sb_list_lock);
+       spin_unlock(&sb->s_inode_list_lock);
        iput(old_inode);
 
 #ifdef CONFIG_QUOTA_DEBUG
@@ -1023,7 +1023,7 @@ static void remove_dquot_ref(struct super_block *sb, int type,
        struct inode *inode;
        int reserved = 0;
 
-       spin_lock(&inode_sb_list_lock);
+       spin_lock(&sb->s_inode_list_lock);
        list_for_each_entry(inode, &sb->s_inodes, i_sb_list) {
                /*
                 *  We have to scan also I_NEW inodes because they can already
@@ -1039,7 +1039,7 @@ static void remove_dquot_ref(struct super_block *sb, int type,
                }
                spin_unlock(&dq_data_lock);
        }
-       spin_unlock(&inode_sb_list_lock);
+       spin_unlock(&sb->s_inode_list_lock);
 #ifdef CONFIG_QUOTA_DEBUG
        if (reserved) {
                printk(KERN_WARNING "VFS (%s): Writes happened after quota"

diff --git a/fs/super.c b/fs/super.c
index b61372354f2bd1cd104d140003859a4333456c79..c808183554a22b16fbdce88293c4ffa9b2f03933 100644 (file)
--- a/fs/super.c
+++ b/fs/super.c
@@ -191,6 +191,7 @@ static struct super_block *alloc_super(struct file_system_type *type, int flags)
        INIT_HLIST_NODE(&s->s_instances);
        INIT_HLIST_BL_HEAD(&s->s_anon);
        INIT_LIST_HEAD(&s->s_inodes);
+       spin_lock_init(&s->s_inode_list_lock);
 
        if (list_lru_init_memcg(&s->s_dentry_lru))
                goto fail;
@@ -399,7 +400,7 @@ void generic_shutdown_super(struct super_block *sb)
                sync_filesystem(sb);
                sb->s_flags &= ~MS_ACTIVE;
 
-               fsnotify_unmount_inodes(&sb->s_inodes);
+               fsnotify_unmount_inodes(sb);
 
                evict_inodes(sb);
 

diff --git a/include/linux/fs.h b/include/linux/fs.h
index 4a40fa8430404aaac210379d066469847bc88334..09bbd38485f98759c316330b143a9760c8faadfb 100644 (file)
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1309,7 +1309,6 @@ struct super_block {
 #endif
        const struct xattr_handler **s_xattr;
 
-       struct list_head        s_inodes;       /* all inodes */
        struct hlist_bl_head    s_anon;         /* anonymous dentries for (nfs) exporting */
        struct list_head        s_mounts;       /* list of mounts; _not_ for fs use */
        struct block_device     *s_bdev;
@@ -1380,6 +1379,10 @@ struct super_block {
         * Indicates how deep in a filesystem stack this SB is
         */
        int s_stack_depth;
+
+       /* s_inode_list_lock protects s_inodes */
+       spinlock_t              s_inode_list_lock ____cacheline_aligned_in_smp;
+       struct list_head        s_inodes;       /* all inodes */
 };
 
 extern struct timespec current_fs_time(struct super_block *sb);

diff --git a/include/linux/fsnotify_backend.h b/include/linux/fsnotify_backend.h
index 65a517dd32f7ad0e23ce5ed69129be657d3b3fdf..0390ee69c4391b0a747a0772d388549fd247eaf0 100644 (file)
--- a/include/linux/fsnotify_backend.h
+++ b/include/linux/fsnotify_backend.h
@@ -357,7 +357,7 @@ extern void fsnotify_clear_marks_by_group_flags(struct fsnotify_group *group, un
 extern void fsnotify_clear_marks_by_group(struct fsnotify_group *group);
 extern void fsnotify_get_mark(struct fsnotify_mark *mark);
 extern void fsnotify_put_mark(struct fsnotify_mark *mark);
-extern void fsnotify_unmount_inodes(struct list_head *list);
+extern void fsnotify_unmount_inodes(struct super_block *sb);
 
 /* put here because inotify does some weird stuff when destroying watches */
 extern void fsnotify_init_event(struct fsnotify_event *event,
@@ -393,7 +393,7 @@ static inline u32 fsnotify_get_cookie(void)
        return 0;
 }
 
-static inline void fsnotify_unmount_inodes(struct list_head *list)
+static inline void fsnotify_unmount_inodes(struct super_block *sb)
 {}
 
 #endif /* CONFIG_FSNOTIFY */