From 4cd9069a0a0e5fb8b007425c937642682ac96c76 Mon Sep 17 00:00:00 2001 From: Richard Kennedy Date: Wed, 25 Apr 2012 14:53:05 +0100 Subject: fs: remove 8 bytes of padding from struct writeback_control on 64 bit builds Reorder structure writeback_control to remove 8 bytes of padding on 64 bit builds, this shrinks its size from 48 to 40 bytes. This structure is always on the stack and uses C99 named initialisation, so should be safe and have a small impact on stack usage. Signed-off-by: Richard Kennedy Signed-off-by: Fengguang Wu --- include/linux/writeback.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'include/linux/writeback.h') diff --git a/include/linux/writeback.h b/include/linux/writeback.h index a2b84f598e2b..3309736ff059 100644 --- a/include/linux/writeback.h +++ b/include/linux/writeback.h @@ -58,7 +58,6 @@ extern const char *wb_reason_name[]; * in a manner such that unspecified fields are set to zero. */ struct writeback_control { - enum writeback_sync_modes sync_mode; long nr_to_write; /* Write this many pages, and decrement this for each page written */ long pages_skipped; /* Pages which were not written */ @@ -71,6 +70,8 @@ struct writeback_control { loff_t range_start; loff_t range_end; + enum writeback_sync_modes sync_mode; + unsigned for_kupdate:1; /* A kupdate writeback */ unsigned for_background:1; /* A background writeback */ unsigned tagged_writepages:1; /* tag-and-write to avoid livelock */ -- cgit v1.2.2 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/writeback.h | 7 +------ 1 file changed, 1 insertion(+), 6 deletions(-) (limited to 'include/linux/writeback.h') diff --git a/include/linux/writeback.h b/include/linux/writeback.h index 3309736ff059..6d0a0fcd80e7 100644 --- a/include/linux/writeback.h +++ b/include/linux/writeback.h @@ -95,6 +95,7 @@ long writeback_inodes_wb(struct bdi_writeback *wb, long nr_pages, enum wb_reason reason); long wb_do_writeback(struct bdi_writeback *wb, int force_wait); void wakeup_flusher_threads(long nr_pages, enum wb_reason reason); +void inode_wait_for_writeback(struct inode *inode); /* writeback.h requires fs.h; it, too, is not included from here. */ static inline void wait_on_inode(struct inode *inode) @@ -102,12 +103,6 @@ static inline void wait_on_inode(struct inode *inode) might_sleep(); wait_on_bit(&inode->i_state, __I_NEW, inode_wait, TASK_UNINTERRUPTIBLE); } -static inline void inode_sync_wait(struct inode *inode) -{ - might_sleep(); - wait_on_bit(&inode->i_state, __I_SYNC, inode_wait, - TASK_UNINTERRUPTIBLE); -} /* -- cgit v1.2.2