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authorJaegeuk Kim <jaegeuk.kim@samsung.com>2013-01-31 15:36:04 +0900
committerJaegeuk Kim <jaegeuk.kim@samsung.com>2013-02-12 07:15:01 +0900
commitd4686d56ec912d55fd8a9d6d509de50de24e90ab (patch)
treef79a5df1353af58c671c58a4eaa7339d7ba80461 /fs/f2fs/f2fs.h
parent369a708c2a6557fabd409cf17a03db271c54931a (diff)
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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 <jaegeuk.kim@samsung.com>
Diffstat (limited to 'fs/f2fs/f2fs.h')
-rw-r--r--fs/f2fs/f2fs.h1
1 files changed, 0 insertions, 1 deletions
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index 975cb44851ab..5022a7d7f7ca 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -847,7 +847,6 @@ long f2fs_ioctl(struct file *, unsigned int, unsigned long);
* inode.c
*/
void f2fs_set_inode_flags(struct inode *);
-struct inode *f2fs_iget_nowait(struct super_block *, unsigned long);
struct inode *f2fs_iget(struct super_block *, unsigned long);
void update_inode(struct inode *, struct page *);
int f2fs_write_inode(struct inode *, struct writeback_control *);