From dbd5768f87ff6fb0a4fe09c4d7b6c4a24de99430 Mon Sep 17 00:00:00 2001 From: Jan Kara Date: Thu, 3 May 2012 14:48:02 +0200 Subject: vfs: Rename end_writeback() to clear_inode() After we moved inode_sync_wait() from end_writeback() it doesn't make sense to call the function end_writeback() anymore. Rename it to clear_inode() which well says what the function really does - set I_CLEAR flag. Signed-off-by: Jan Kara Signed-off-by: Fengguang Wu --- include/linux/fs.h | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'include/linux/fs.h') diff --git a/include/linux/fs.h b/include/linux/fs.h index 8de675523e46..c79316c79ee3 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -1744,8 +1744,8 @@ struct super_operations { * I_FREEING Set when inode is about to be freed but still has dirty * pages or buffers attached or the inode itself is still * dirty. - * I_CLEAR Added by end_writeback(). In this state the inode is clean - * and can be destroyed. Inode keeps I_FREEING. + * I_CLEAR Added by clear_inode(). In this state the inode is + * clean and can be destroyed. Inode keeps I_FREEING. * * Inodes that are I_WILL_FREE, I_FREEING or I_CLEAR are * prohibited for many purposes. iget() must wait for @@ -2328,7 +2328,7 @@ extern unsigned int get_next_ino(void); extern void __iget(struct inode * inode); extern void iget_failed(struct inode *); -extern void end_writeback(struct inode *); +extern void clear_inode(struct inode *); extern void __destroy_inode(struct inode *); extern struct inode *new_inode_pseudo(struct super_block *sb); extern struct inode *new_inode(struct super_block *sb); -- cgit From 169ebd90131b2ffca74bb2dbe7eeacd39fb83714 Mon Sep 17 00:00:00 2001 From: Jan Kara Date: Thu, 3 May 2012 14:48:03 +0200 Subject: writeback: Avoid iput() from flusher thread Doing iput() from flusher thread (writeback_sb_inodes()) can create problems because iput() can do a lot of work - for example truncate the inode if it's the last iput on unlinked file. Some filesystems depend on flusher thread progressing (e.g. because they need to flush delay allocated blocks to reduce allocation uncertainty) and so flusher thread doing truncate creates interesting dependencies and possibilities for deadlocks. We get rid of iput() in flusher thread by using the fact that I_SYNC inode flag effectively pins the inode in memory. So if we take care to either hold i_lock or have I_SYNC set, we can get away without taking inode reference in writeback_sb_inodes(). As a side effect of these changes, we also fix possible use-after-free in wb_writeback() because inode_wait_for_writeback() call could try to reacquire i_lock on the inode that was already free. Signed-off-by: Jan Kara Signed-off-by: Fengguang Wu --- include/linux/fs.h | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) (limited to 'include/linux/fs.h') diff --git a/include/linux/fs.h b/include/linux/fs.h index c79316c79ee3..1c71e7f4d234 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -1753,9 +1753,10 @@ struct super_operations { * anew. Other functions will just ignore such inodes, * if appropriate. I_NEW is used for waiting. * - * I_SYNC Synchonized write of dirty inode data. The bits is - * set during data writeback, and cleared with a wakeup - * on the bit address once it is done. + * I_SYNC Writeback of inode is running. The bit is set during + * data writeback, and cleared with a wakeup on the bit + * address once it is done. The bit is also used to pin + * the inode in memory for flusher thread. * * I_REFERENCED Marks the inode as recently references on the LRU list. * -- cgit