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/file.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) (limited to 'fs/f2fs/file.c') diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c index 6cdab2c64fc6..3efa4739b00c 100644 --- a/fs/f2fs/file.c +++ b/fs/f2fs/file.c @@ -298,8 +298,6 @@ void f2fs_truncate(struct inode *inode) inode->i_mtime = inode->i_ctime = CURRENT_TIME; mark_inode_dirty(inode); } - - f2fs_balance_fs(F2FS_SB(inode->i_sb)); } static int f2fs_getattr(struct vfsmount *mnt, @@ -356,6 +354,7 @@ int f2fs_setattr(struct dentry *dentry, struct iattr *attr) attr->ia_size != i_size_read(inode)) { truncate_setsize(inode, attr->ia_size); f2fs_truncate(inode); + f2fs_balance_fs(F2FS_SB(inode->i_sb)); } __setattr_copy(inode, attr); -- cgit v1.2.3-70-g09d2