From d4cf109f05ff04c6f5065c3e14165ef01a57dd53 Mon Sep 17 00:00:00 2001 From: Dave Kleikamp Date: Fri, 6 Feb 2009 14:59:26 -0600 Subject: vfs: Don't call attach_nobh_buffers() with an empty list This is a modification of a patch by Bill Pemberton nobh_write_end() could call attach_nobh_buffers() with head == NULL. This would result in a trap when attach_nobh_buffers() attempted to access bh->b_this_page. This can be illustrated by running the writev01 testcase from LTP on jfs. This error was introduced by commit 5b41e74a "vfs: fix data leak in nobh_write_end()". That patch did not take into account that if PageMappedToDisk() is true upon entry to nobh_write_begin(), then no buffers will be allocated for the page. In that case, we won't have to worry about a failed write leaving unitialized data in the page. Of course, head != NULL implies !page_has_buffers(page), so no need to test both. Signed-off-by: Dave Kleikamp Cc: Bill Pemberton Cc: Dmitri Monakhov Signed-off-by: Linus Torvalds --- fs/buffer.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'fs/buffer.c') diff --git a/fs/buffer.c b/fs/buffer.c index b58208f1640a..665d446b25bc 100644 --- a/fs/buffer.c +++ b/fs/buffer.c @@ -2688,7 +2688,7 @@ int nobh_write_end(struct file *file, struct address_space *mapping, struct buffer_head *bh; BUG_ON(fsdata != NULL && page_has_buffers(page)); - if (unlikely(copied < len) && !page_has_buffers(page)) + if (unlikely(copied < len) && head) attach_nobh_buffers(page, head); if (page_has_buffers(page)) return generic_write_end(file, mapping, pos, len, -- cgit v1.2.2 From 78f707bfc723552e8309b7c38a8d0cc51012e813 Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Tue, 17 Feb 2009 13:59:08 +0100 Subject: block: revert part of 18ce3751ccd488c78d3827e9f6bf54e6322676fb The above commit added WRITE_SYNC and switched various places to using that for committing writes that will be waited upon immediately after submission. However, this causes a performance regression with AS and CFQ for ext3 at least, since sync_dirty_buffer() will submit some writes with WRITE_SYNC while ext3 has sumitted others dependent writes without the sync flag set. This causes excessive anticipation/idling in the IO scheduler because sync and async writes get interleaved, causing a big performance regression for the below test case (which is meant to simulate sqlite like behaviour). ---- test case ---- int main(int argc, char **argv) { int fdes, i; FILE *fp; struct timeval start; struct timeval end; struct timeval res; gettimeofday(&start, NULL); for (i=0; i --- fs/buffer.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'fs/buffer.c') diff --git a/fs/buffer.c b/fs/buffer.c index 665d446b25bc..62b57e330b69 100644 --- a/fs/buffer.c +++ b/fs/buffer.c @@ -3108,7 +3108,7 @@ int sync_dirty_buffer(struct buffer_head *bh) if (test_clear_buffer_dirty(bh)) { get_bh(bh); bh->b_end_io = end_buffer_write_sync; - ret = submit_bh(WRITE_SYNC, bh); + ret = submit_bh(WRITE, bh); wait_on_buffer(bh); if (buffer_eopnotsupp(bh)) { clear_buffer_eopnotsupp(bh); -- cgit v1.2.2 From 1cf6e7d83bf334cc5916137862c920a97aabc018 Mon Sep 17 00:00:00 2001 From: Nick Piggin Date: Wed, 18 Feb 2009 14:48:18 -0800 Subject: mm: task dirty accounting fix YAMAMOTO-san noticed that task_dirty_inc doesn't seem to be called properly for cases where set_page_dirty is not used to dirty a page (eg. mark_buffer_dirty). Additionally, there is some inconsistency about when task_dirty_inc is called. It is used for dirty balancing, however it even gets called for __set_page_dirty_no_writeback. So rather than increment it in a set_page_dirty wrapper, move it down to exactly where the dirty page accounting stats are incremented. Cc: YAMAMOTO Takashi Signed-off-by: Nick Piggin Acked-by: Peter Zijlstra Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/buffer.c | 1 + 1 file changed, 1 insertion(+) (limited to 'fs/buffer.c') diff --git a/fs/buffer.c b/fs/buffer.c index 665d446b25bc..ff4d1cdd779b 100644 --- a/fs/buffer.c +++ b/fs/buffer.c @@ -777,6 +777,7 @@ static int __set_page_dirty(struct page *page, __inc_zone_page_state(page, NR_FILE_DIRTY); __inc_bdi_stat(mapping->backing_dev_info, BDI_RECLAIMABLE); + task_dirty_inc(current); task_io_account_write(PAGE_CACHE_SIZE); } radix_tree_tag_set(&mapping->page_tree, -- cgit v1.2.2