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Fengguang Wu authored
patch c06a018f in mainline. 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: [<ffffffff8027e920>] cancel_dirty_page+0xd0/0xf0 [<ffffffff8816d470>] :reiserfs:reiserfs_cut_from_item+0x660/0x710 [<ffffffff8816d791>] :reiserfs:reiserfs_do_truncate+0x271/0x530 [<ffffffff8815872d>] :reiserfs:reiserfs_truncate_file+0xfd/0x3b0 [<ffffffff8815d3d0>] :reiserfs:reiserfs_file_release+0x1e0/0x340 [<ffffffff802a187c>] __fput+0xcc/0x1b0 [<ffffffff802a1ba6>] fput+0x16/0x20 [<ffffffff8029e676>] filp_close+0x56/0x90 [<ffffffff8029fe0d>] sys_close+0xad/0x110 [<ffffffff8020c41e>] 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 <maximlevitsky@gmail.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Jeff Mahoney <jeffm@suse.com> Signed-off-by: Fengguang Wu <wfg@mail.ustc.edu.cn> Reviewed-by: Chris Mason <chris.mason@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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