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/inode.c | 33 --------------------------------- 1 file changed, 33 deletions(-) (limited to 'fs/f2fs/inode.c') diff --git a/fs/f2fs/inode.c b/fs/f2fs/inode.c index 62433c63e2db..ddae412d30c8 100644 --- a/fs/f2fs/inode.c +++ b/fs/f2fs/inode.c @@ -16,11 +16,6 @@ #include "f2fs.h" #include "node.h" -struct f2fs_iget_args { - u64 ino; - int on_free; -}; - void f2fs_set_inode_flags(struct inode *inode) { unsigned int flags = F2FS_I(inode)->i_flags; @@ -40,34 +35,6 @@ void f2fs_set_inode_flags(struct inode *inode) inode->i_flags |= S_DIRSYNC; } -static int f2fs_iget_test(struct inode *inode, void *data) -{ - struct f2fs_iget_args *args = data; - - if (inode->i_ino != args->ino) - return 0; - if (inode->i_state & (I_FREEING | I_WILL_FREE)) { - args->on_free = 1; - return 0; - } - return 1; -} - -struct inode *f2fs_iget_nowait(struct super_block *sb, unsigned long ino) -{ - struct f2fs_iget_args args = { - .ino = ino, - .on_free = 0 - }; - struct inode *inode = ilookup5(sb, ino, f2fs_iget_test, &args); - - if (inode) - return inode; - if (!args.on_free) - return f2fs_iget(sb, ino); - return ERR_PTR(-ENOENT); -} - static int do_read_inode(struct inode *inode) { struct f2fs_sb_info *sbi = F2FS_SB(inode->i_sb); -- cgit v1.2.3