From d4686d56ec912d55fd8a9d6d509de50de24e90ab Mon Sep 17 00:00:00 2001 From: Jaegeuk Kim Date: Thu, 31 Jan 2013 15:36:04 +0900 Subject: f2fs: avoid balanc_fs during evict_inode 1. Background Previously, if f2fs tries to move data blocks of an *evicting* inode during the cleaning process, it stops the process incompletely and then restarts the whole process, since it needs a locked inode to grab victim data pages in its address space. In order to get a locked inode, iget_locked() by f2fs_iget() is normally used, but, it waits if the inode is on freeing. So, here is a deadlock scenario. 1. f2fs_evict_inode() <- inode "A" 2. f2fs_balance_fs() 3. f2fs_gc() 4. gc_data_segment() 5. f2fs_iget() <- inode "A" too! If step #1 and #5 treat a same inode "A", step #5 would fall into deadlock since the inode "A" is on freeing. In order to resolve this, f2fs_iget_nowait() which skips __wait_on_freeing_inode() was introduced in step #5, and stops f2fs_gc() to complete f2fs_evict_inode(). 1. f2fs_evict_inode() <- inode "A" 2. f2fs_balance_fs() 3. f2fs_gc() 4. gc_data_segment() 5. f2fs_iget_nowait() <- inode "A", then stop f2fs_gc() w/ -ENOENT 2. Problem and Solution In the above scenario, however, f2fs cannot finish f2fs_evict_inode() only if: o there are not enough free sections, and o f2fs_gc() tries to move data blocks of the *evicting* inode repeatedly. So, the final solution is to use f2fs_iget() and remove f2fs_balance_fs() in f2fs_evict_inode(). The f2fs_evict_inode() actually truncates all the data and node blocks, which means that it doesn't produce any dirty node pages accordingly. So, we don't need to do f2fs_balance_fs() in practical. Signed-off-by: Jaegeuk Kim --- fs/f2fs/recovery.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'fs/f2fs/recovery.c') diff --git a/fs/f2fs/recovery.c b/fs/f2fs/recovery.c index f42e4060b399..e2a3e1a8eae9 100644 --- a/fs/f2fs/recovery.c +++ b/fs/f2fs/recovery.c @@ -226,7 +226,7 @@ static void check_index_in_prev_nodes(struct f2fs_sb_info *sbi, f2fs_put_page(node_page, 1); /* Deallocate previous index in the node page */ - inode = f2fs_iget_nowait(sbi->sb, ino); + inode = f2fs_iget(sbi->sb, ino); if (IS_ERR(inode)) return; -- cgit v1.2.3