4.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: Lukas Czerner <lczerner@xxxxxxxxxx> commit 9705acd63b125dee8b15c705216d7186daea4625 upstream. On delalloc enabled file system on invalidatepage operation in ext4_da_page_release_reservation() we want to clear the delayed buffer and remove the extent covering the delayed buffer from the extent status tree. However currently there is a bug where on the systems with page size > block size we will always remove extents from the start of the page regardless where the actual delayed buffers are positioned in the page. This leads to the errors like this: EXT4-fs warning (device loop0): ext4_da_release_space:1225: ext4_da_release_space: ino 13, to_free 1 with only 0 reserved data blocks This however can cause data loss on writeback time if the file system is in ENOSPC condition because we're releasing reservation for someones else delayed buffer. Fix this by only removing extents that corresponds to the part of the page we want to invalidate. This problem is reproducible by the following fio receipt (however I was only able to reproduce it with fio-2.1 or older. [global] bs=8k iodepth=1024 iodepth_batch=60 randrepeat=1 size=1m directory=/mnt/test numjobs=20 [job1] ioengine=sync bs=1k direct=1 rw=randread filename=file1:file2 [job2] ioengine=libaio rw=randwrite direct=1 filename=file1:file2 [job3] bs=1k ioengine=posixaio rw=randwrite direct=1 filename=file1:file2 [job5] bs=1k ioengine=sync rw=randread filename=file1:file2 [job7] ioengine=libaio rw=randwrite filename=file1:file2 [job8] ioengine=posixaio rw=randwrite filename=file1:file2 [job10] ioengine=mmap rw=randwrite bs=1k filename=file1:file2 [job11] ioengine=mmap rw=randwrite direct=1 filename=file1:file2 Signed-off-by: Lukas Czerner <lczerner@xxxxxxxxxx> Signed-off-by: Theodore Ts'o <tytso@xxxxxxx> Reviewed-by: Jan Kara <jack@xxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- fs/ext4/inode.c | 15 ++++++++++++--- 1 file changed, 12 insertions(+), 3 deletions(-) --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -1342,7 +1342,7 @@ static void ext4_da_page_release_reserva unsigned int offset, unsigned int length) { - int to_release = 0; + int to_release = 0, contiguous_blks = 0; struct buffer_head *head, *bh; unsigned int curr_off = 0; struct inode *inode = page->mapping->host; @@ -1363,14 +1363,23 @@ static void ext4_da_page_release_reserva if ((offset <= curr_off) && (buffer_delay(bh))) { to_release++; + contiguous_blks++; clear_buffer_delay(bh); + } else if (contiguous_blks) { + lblk = page->index << + (PAGE_CACHE_SHIFT - inode->i_blkbits); + lblk += (curr_off >> inode->i_blkbits) - + contiguous_blks; + ext4_es_remove_extent(inode, lblk, contiguous_blks); + contiguous_blks = 0; } curr_off = next_off; } while ((bh = bh->b_this_page) != head); - if (to_release) { + if (contiguous_blks) { lblk = page->index << (PAGE_CACHE_SHIFT - inode->i_blkbits); - ext4_es_remove_extent(inode, lblk, to_release); + lblk += (curr_off >> inode->i_blkbits) - contiguous_blks; + ext4_es_remove_extent(inode, lblk, contiguous_blks); } /* If we have released all the blocks belonging to a cluster, then we -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html