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Date: Wed, 31 Jul 2013 16:48:08 +0200
From: Jan Kara <jack@...e.cz>
To: Dave Chinner <david@...morbit.com>
Cc: linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
akpm@...ux-foundation.org, davej@...hat.com,
viro@...iv.linux.org.uk, jack@...e.cz, glommer@...allels.com
Subject: Re: [PATCH 03/11] inode: convert inode_sb_list_lock to per-sb
On Wed 31-07-13 14:15:42, Dave Chinner wrote:
> From: Dave Chinner <dchinner@...hat.com>
>
> 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.
Looks good. You can add:
Reviewed-by: Jan Kara <jack@...e.cz>
Honza
>
> Signed-off-by: Dave Chinner <dchinner@...hat.com>
> ---
> fs/block_dev.c | 12 ++++++------
> fs/drop_caches.c | 10 ++++++----
> fs/fs-writeback.c | 12 ++++++------
> fs/inode.c | 28 +++++++++++++---------------
> fs/internal.h | 1 -
> fs/notify/inode_mark.c | 20 ++++++++++----------
> fs/quota/dquot.c | 16 ++++++++--------
> fs/super.c | 3 ++-
> include/linux/fs.h | 5 ++++-
> include/linux/fsnotify_backend.h | 2 +-
> 10 files changed, 56 insertions(+), 53 deletions(-)
>
> diff --git a/fs/block_dev.c b/fs/block_dev.c
> index c7bda5c..c39c0f3 100644
> --- a/fs/block_dev.c
> +++ b/fs/block_dev.c
> @@ -1669,7 +1669,7 @@ 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;
>
> @@ -1681,13 +1681,13 @@ 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);
> @@ -1695,8 +1695,8 @@ 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 9fd702f..f1be790 100644
> --- 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 1d23d9a..ca66dc8 100644
> --- a/fs/fs-writeback.c
> +++ b/fs/fs-writeback.c
> @@ -1217,7 +1217,7 @@ 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,
> @@ -1237,14 +1237,14 @@ 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);
> @@ -1254,9 +1254,9 @@ 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 e315c0a..cd10287 100644
> --- a/fs/inode.c
> +++ b/fs/inode.c
> @@ -27,8 +27,8 @@
> * 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}, inode->i_wb_list
> * inode_hash_lock protects:
> @@ -36,7 +36,7 @@
> *
> * Lock ordering:
> *
> - * inode_sb_list_lock
> + * inode->i_sb->s_inode_list_lock
> * inode->i_lock
> * Inode LRU list locks
> *
> @@ -44,7 +44,7 @@
> * inode->i_lock
> *
> * inode_hash_lock
> - * inode_sb_list_lock
> + * inode->i_sb->s_inode_list_lock
> * inode->i_lock
> *
> * iunique_lock
> @@ -56,8 +56,6 @@ 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.
> @@ -432,18 +430,18 @@ 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);
> }
> }
>
> @@ -600,7 +598,7 @@ 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;
> @@ -616,7 +614,7 @@ 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);
> }
> @@ -637,7 +635,7 @@ 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)) {
> @@ -660,7 +658,7 @@ 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);
>
> @@ -901,7 +899,7 @@ 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 0b0db70..bdc0e86 100644
> --- a/fs/internal.h
> +++ b/fs/internal.h
> @@ -110,7 +110,6 @@ extern int open_check_o_direct(struct file *f);
> /*
> * inode.c
> */
> -extern spinlock_t inode_sb_list_lock;
> extern long prune_icache_sb(struct super_block *sb, unsigned long nr_to_scan,
> int nid);
> extern void inode_add_lru(struct inode *inode);
> diff --git a/fs/notify/inode_mark.c b/fs/notify/inode_mark.c
> index 74825be..fac139a 100644
> --- a/fs/notify/inode_mark.c
> +++ b/fs/notify/inode_mark.c
> @@ -242,17 +242,17 @@ out:
>
> /**
> * 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;
>
> /*
> @@ -288,7 +288,7 @@ void fsnotify_unmount_inodes(struct list_head *list)
> spin_unlock(&inode->i_lock);
>
> /* In case the dropping of a reference would nuke next_i. */
> - if ((&next_i->i_sb_list != list) &&
> + if ((&next_i->i_sb_list != &sb->s_inodes) &&
> atomic_read(&next_i->i_count)) {
> spin_lock(&next_i->i_lock);
> if (!(next_i->i_state & (I_FREEING | I_WILL_FREE))) {
> @@ -299,11 +299,11 @@ void fsnotify_unmount_inodes(struct list_head *list)
> }
>
> /*
> - * We can safely drop inode_sb_list_lock here because we hold
> + * We can safely drop s_inode_list_lock here because we hold
> * references on both inode and next_i. 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);
> @@ -315,7 +315,7 @@ 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 017eaea..fe93be2 100644
> --- a/fs/quota/dquot.c
> +++ b/fs/quota/dquot.c
> @@ -909,7 +909,7 @@ 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)) ||
> @@ -920,7 +920,7 @@ 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))
> @@ -932,15 +932,15 @@ 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
> @@ -1021,7 +1021,7 @@ 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
> @@ -1035,7 +1035,7 @@ static void remove_dquot_ref(struct super_block *sb, int type,
> remove_inode_dquot_ref(inode, type, tofree_head);
> }
> }
> - 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 09da975..d4d753e 100644
> --- a/fs/super.c
> +++ b/fs/super.c
> @@ -201,6 +201,7 @@ 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(&s->s_dentry_lru))
> goto err_out;
> @@ -441,7 +442,7 @@ 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 51cf6ed..923b465 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -1263,7 +1263,6 @@ 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 */
> #ifdef CONFIG_SMP
> struct list_head __percpu *s_files;
> @@ -1328,6 +1327,10 @@ struct super_block {
> */
> struct list_lru s_dentry_lru ____cacheline_aligned_in_smp;
> struct list_lru s_inode_lru ____cacheline_aligned_in_smp;
> +
> + /* 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 4b2ee8d..3d58028 100644
> --- a/include/linux/fsnotify_backend.h
> +++ b/include/linux/fsnotify_backend.h
> @@ -427,7 +427,7 @@ 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 struct fsnotify_event *fsnotify_create_event(struct inode *to_tell, __u32 mask,
> --
> 1.8.3.2
>
--
Jan Kara <jack@...e.cz>
SUSE Labs, CR
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