change log from v1:
o found another deadlock case, so change the approach
From 145b6ee0b2523bad0e28c09f4ac5bb050cd22085 Mon Sep 17 00:00:00 2001
From: Jaegeuk Kim <jaegeuk.kim@xxxxxxxxxxx>
Date: Tue, 30 Apr 2013 11:33:27 +0900
Subject: [PATCH] f2fs: avoid deadlock during evict after f2fs_gc
Cc: linux-fsdevel@xxxxxxxxxxxxxxx, linux-kernel@xxxxxxxxxxxxxxx,
linux-f2fs-devel@xxxxxxxxxxxxxxxxxxxxx
o Deadlock case #1
Thread 1:
- writeback_sb_inodes
- do_writepages
- f2fs_write_data_pages
- write_cache_pages
- f2fs_write_data_page
- f2fs_balance_fs
- wait mutex_lock(gc_mutex)
Thread 2:
- f2fs_balance_fs
- mutex_lock(gc_mutex)
- f2fs_gc
- f2fs_iget
- wait iget_locked(inode->i_lock)
Thread 3:
- do_unlinkat
- iput
- lock(inode->i_lock)
- evict
- inode_wait_for_writeback
o Deadlock case #2
Thread 1:
- __writeback_single_inode
: set I_SYNC
- do_writepages
- f2fs_write_data_page
- f2fs_balance_fs
- f2fs_gc
- iput
- evict
- inode_wait_for_writeback(I_SYNC)
In order to avoid this, even though iput is called with the
zero-reference
count, we need to stop the eviction procedure if the inode is on
writeback.
So this patch links f2fs_drop_inode which checks the I_SYNC flag.
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@xxxxxxxxxxx>
---
fs/f2fs/super.c | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index b015b6c..e1c54e4 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -99,6 +99,13 @@ static struct inode *f2fs_alloc_inode(struct
super_block *sb)
return &fi->vfs_inode;
}
+static int f2fs_drop_inode(struct inode *inode)
+{
+ if (inode->i_state & I_SYNC)
+ return 0;
+ return generic_drop_inode(inode);
+}
+
static void f2fs_i_callback(struct rcu_head *head)
{
struct inode *inode = container_of(head, struct inode, i_rcu);
@@ -233,6 +240,7 @@ static int f2fs_show_options(struct seq_file *seq,
struct dentry *root)
static struct super_operations f2fs_sops = {
.alloc_inode = f2fs_alloc_inode,
+ .drop_inode = f2fs_drop_inode,
.destroy_inode = f2fs_destroy_inode,
.write_inode = f2fs_write_inode,
.show_options = f2fs_show_options,
--
1.8.1.3.566.gaa39828
--
Jaegeuk Kim
Samsung
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