The patch titled fs/inode.c: properly init address_space->writeback_index has been added to the -mm tree. Its filename is fs-inodec-properly-init-address_space-writeback_index.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/SubmitChecklist when testing your code *** See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find out what to do about this The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/ ------------------------------------------------------ Subject: fs/inode.c: properly init address_space->writeback_index From: Chris Mason <chris.mason@xxxxxxxxxx> write_cache_pages() uses i_mapping->writeback_index to pick up where it left off the last time a given inode was found by pdflush or balance_dirty_pages (or anyone else who sets wbc->range_cyclic) alloc_inode() should set it to a sane value so that writeback doesn't start in the middle of a file. It is somewhat difficult to notice the bug since write_cache_pages will loop around to the start of the file and the elevator helps hide the resulting seeks. For whatever reason, Btrfs hits this often. Unpatched, untarring 30 copies of the linux kernel in series runs at 47MB/s on a single sata drive. With this fix, it jumps to 62MB/s. Signed-off-by: Chris Mason <chris.mason@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- fs/inode.c | 1 + 1 file changed, 1 insertion(+) diff -puN fs/inode.c~fs-inodec-properly-init-address_space-writeback_index fs/inode.c --- a/fs/inode.c~fs-inodec-properly-init-address_space-writeback_index +++ a/fs/inode.c @@ -166,6 +166,7 @@ static struct inode *alloc_inode(struct mapping_set_gfp_mask(mapping, GFP_HIGHUSER_PAGECACHE); mapping->assoc_mapping = NULL; mapping->backing_dev_info = &default_backing_dev_info; + mapping->writeback_index = 0; /* * If the block_device provides a backing_dev_info for client _ Patches currently in -mm which might be from chris.mason@xxxxxxxxxx are fs-inodec-properly-init-address_space-writeback_index.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html