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Subject[PATCH] Invalidate_inodes can be very slow
Date
I'm not sure whom this patch should be send to, so I'm posting it here.

this patch fixes the problem that huge inode cache
can make invalidate_inodes() calls very long. Meanwhile
lock_kernel() and inode_lock are being held and system
can freeze for seconds.
I detected this problem on kernel with 4gb split. When inode cache
was 2.5Gb (1,000,000 of inodes in cache) it took seconds to umount
or turn quota off.
This patch is against 2.4.22 kernel. But as far as I can see the problem
still exists in 2.6 kernels.
This patch introduces per-super block inode list which makes
possible to scan sb's only inodes when doing umount.

Kirill
--- ./fs/super.c.ii 2003-08-25 15:44:43.000000000 +0400
+++ ./fs/super.c 2003-10-13 12:08:43.000000000 +0400
@@ -271,6 +271,7 @@ static struct super_block *alloc_super(v
INIT_LIST_HEAD(&s->s_locked_inodes);
INIT_LIST_HEAD(&s->s_files);
INIT_LIST_HEAD(&s->s_instances);
+ INIT_LIST_HEAD(&s->s_inodes);
init_rwsem(&s->s_umount);
sema_init(&s->s_lock, 1);
down_write(&s->s_umount);
--- ./fs/inode.c.ii 2003-08-25 15:44:43.000000000 +0400
+++ ./fs/inode.c 2003-10-13 12:18:25.000000000 +0400
@@ -604,7 +604,7 @@ static void dispose_list(struct list_hea
/*
* Invalidate all inodes for a device.
*/
-static int invalidate_list(struct list_head *head, struct super_block * sb, struct list_head * dispose)
+static int invalidate_list(struct list_head *head, struct list_head * dispose)
{
struct list_head *next;
int busy = 0, count = 0;
@@ -617,12 +617,11 @@ static int invalidate_list(struct list_h
next = next->next;
if (tmp == head)
break;
- inode = list_entry(tmp, struct inode, i_list);
- if (inode->i_sb != sb)
- continue;
+ inode = list_entry(tmp, struct inode, i_sb_list);
invalidate_inode_buffers(inode);
if (!atomic_read(&inode->i_count)) {
list_del_init(&inode->i_hash);
+ list_del(&inode->i_sb_list);
list_del(&inode->i_list);
list_add(&inode->i_list, dispose);
inode->i_state |= I_FREEING;
@@ -659,10 +658,7 @@ int invalidate_inodes(struct super_block
LIST_HEAD(throw_away);

spin_lock(&inode_lock);
- busy = invalidate_list(&inode_in_use, sb, &throw_away);
- busy |= invalidate_list(&inode_unused, sb, &throw_away);
- busy |= invalidate_list(&sb->s_dirty, sb, &throw_away);
- busy |= invalidate_list(&sb->s_locked_inodes, sb, &throw_away);
+ busy = invalidate_list(&sb->s_inodes, &throw_away);
spin_unlock(&inode_lock);

dispose_list(&throw_away);
@@ -738,6 +734,7 @@ void prune_icache(int goal)
list_del(tmp);
list_del(&inode->i_hash);
INIT_LIST_HEAD(&inode->i_hash);
+ list_del(&inode->i_sb_list);
list_add(tmp, freeable);
inode->i_state |= I_FREEING;
count++;
@@ -827,6 +824,7 @@ struct inode * new_inode(struct super_bl
spin_lock(&inode_lock);
inodes_stat.nr_inodes++;
list_add(&inode->i_list, &inode_in_use);
+ list_add(&inode->i_sb_list, &sb->s_inodes);
inode->i_ino = ++last_ino;
inode->i_state = 0;
spin_unlock(&inode_lock);
@@ -854,6 +852,7 @@ static struct inode * get_new_inode(stru
if (!old) {
inodes_stat.nr_inodes++;
list_add(&inode->i_list, &inode_in_use);
+ list_add(&inode->i_sb_list, &sb->s_inodes);
list_add(&inode->i_hash, head);
inode->i_ino = ino;
inode->i_state = I_LOCK;
@@ -1046,6 +1045,7 @@ void iput(struct inode *inode)
INIT_LIST_HEAD(&inode->i_hash);
list_del(&inode->i_list);
INIT_LIST_HEAD(&inode->i_list);
+ list_del(&inode->i_sb_list);
inode->i_state|=I_FREEING;
inodes_stat.nr_inodes--;
spin_unlock(&inode_lock);
@@ -1079,6 +1079,7 @@ void iput(struct inode *inode)
list_del_init(&inode->i_hash);
}
list_del_init(&inode->i_list);
+ list_del(&inode->i_sb_list);
inode->i_state|=I_FREEING;
inodes_stat.nr_inodes--;
spin_unlock(&inode_lock);
@@ -1239,26 +1240,10 @@ void remove_dquot_ref(struct super_block
lock_kernel(); /* This lock is for quota code */
spin_lock(&inode_lock); /* This lock is for inodes code */

- list_for_each(act_head, &inode_in_use) {
- inode = list_entry(act_head, struct inode, i_list);
- if (inode->i_sb == sb && IS_QUOTAINIT(inode))
- remove_inode_dquot_ref(inode, type, &tofree_head);
- }
- list_for_each(act_head, &inode_unused) {
- inode = list_entry(act_head, struct inode, i_list);
- if (inode->i_sb == sb && IS_QUOTAINIT(inode))
- remove_inode_dquot_ref(inode, type, &tofree_head);
- }
- list_for_each(act_head, &sb->s_dirty) {
- inode = list_entry(act_head, struct inode, i_list);
+ list_for_each_entry(inode, act_head, &sb->s_inodes)
if (IS_QUOTAINIT(inode))
remove_inode_dquot_ref(inode, type, &tofree_head);
- }
- list_for_each(act_head, &sb->s_locked_inodes) {
- inode = list_entry(act_head, struct inode, i_list);
- if (IS_QUOTAINIT(inode))
- remove_inode_dquot_ref(inode, type, &tofree_head);
- }
+
spin_unlock(&inode_lock);
unlock_kernel();

--- ./include/linux/fs.h.ii 2003-08-25 15:44:44.000000000 +0400
+++ ./include/linux/fs.h 2003-10-13 12:23:53.000000000 +0400
@@ -438,6 +438,7 @@ struct block_device {
struct inode {
struct list_head i_hash;
struct list_head i_list;
+ struct list_head i_sb_list;
struct list_head i_dentry;

struct list_head i_dirty_buffers;
@@ -756,6 +757,7 @@ struct super_block {
int s_count;
atomic_t s_active;

+ struct list_head s_inodes; /* all inodes */
struct list_head s_dirty; /* dirty inodes */
struct list_head s_locked_inodes;/* inodes being synced */
struct list_head s_files;
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