From c06a018fa5362fa9ed0768bd747c0fab26bc8849 Mon Sep 17 00:00:00 2001 From: Fengguang Wu Date: Wed, 14 Nov 2007 16:59:54 -0800 Subject: reiserfs: don't drop PG_dirty when releasing sub-page-sized dirty file This is not a new problem in 2.6.23-git17. 2.6.22/2.6.23 is buggy in the same way. Reiserfs could accumulate dirty sub-page-size files until umount time. They cannot be synced to disk by pdflush routines or explicit `sync' commands. Only `umount' can do the trick. The direct cause is: the dirty page's PG_dirty is wrongly _cleared_. Call trace: [] cancel_dirty_page+0xd0/0xf0 [] :reiserfs:reiserfs_cut_from_item+0x660/0x710 [] :reiserfs:reiserfs_do_truncate+0x271/0x530 [] :reiserfs:reiserfs_truncate_file+0xfd/0x3b0 [] :reiserfs:reiserfs_file_release+0x1e0/0x340 [] __fput+0xcc/0x1b0 [] fput+0x16/0x20 [] filp_close+0x56/0x90 [] sys_close+0xad/0x110 [] system_call+0x7e/0x83 Fix the bug by removing the cancel_dirty_page() call. Tests show that it causes no bad behaviors on various write sizes. === for the patient === Here are more detailed demonstrations of the problem. 1) the page has both PG_dirty(D)/PAGECACHE_TAG_DIRTY(d) after being written to; and then only PAGECACHE_TAG_DIRTY(d) remains after the file is closed. ------------------------------ screen 0 ------------------------------ [T0] root /home/wfg# cat > /test/tiny [T1] hi [T2] root /home/wfg# ------------------------------ screen 1 ------------------------------ [T1] root /home/wfg# echo /test/tiny > /proc/filecache [T1] root /home/wfg# cat /proc/filecache # file /test/tiny # flags R:referenced A:active M:mmap U:uptodate D:dirty W:writeback O:owner B:buffer d:dirty w:writeback # idx len state refcnt 0 1 ___UD__Bd_ 2 [T2] root /home/wfg# cat /proc/filecache # file /test/tiny # flags R:referenced A:active M:mmap U:uptodate D:dirty W:writeback O:owner B:buffer d:dirty w:writeback # idx len state refcnt 0 1 ___U___Bd_ 2 2) note the non-zero 'cancelled_write_bytes' after /tmp/hi is copied. ------------------------------ screen 0 ------------------------------ [T0] root /home/wfg# echo hi > /tmp/hi [T1] root /home/wfg# cp /tmp/hi /dev/stdin /test [T2] hi [T3] root /home/wfg# ------------------------------ screen 1 ------------------------------ [T1] root /proc/4397# cd /proc/`pidof cp` [T1] root /proc/4713# cat io rchar: 8396 wchar: 3 syscr: 20 syscw: 1 read_bytes: 0 write_bytes: 20480 cancelled_write_bytes: 4096 [T2] root /proc/4713# cat io rchar: 8399 wchar: 6 syscr: 21 syscw: 2 read_bytes: 0 write_bytes: 24576 cancelled_write_bytes: 4096 //Question: the 'write_bytes' is a bit more than expected ;-) Tested-by: Maxim Levitsky Cc: Peter Zijlstra Cc: Jeff Mahoney Signed-off-by: Fengguang Wu Reviewed-by: Chris Mason Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/reiserfs/stree.c | 3 --- 1 file changed, 3 deletions(-) (limited to 'fs/reiserfs') diff --git a/fs/reiserfs/stree.c b/fs/reiserfs/stree.c index ca41567d7890..d2db2417b2bd 100644 --- a/fs/reiserfs/stree.c +++ b/fs/reiserfs/stree.c @@ -1458,9 +1458,6 @@ static void unmap_buffers(struct page *page, loff_t pos) } bh = next; } while (bh != head); - if (PAGE_SIZE == bh->b_size) { - cancel_dirty_page(page, PAGE_CACHE_SIZE); - } } } } -- cgit v1.2.1