From 9f00d109efeaf4d12d56c8e46cd13af80e344f97 Mon Sep 17 00:00:00 2001 From: Dmitry Monakhov Date: Fri, 5 Oct 2012 11:32:02 -0400 Subject: [PATCH 12/13] ext4: serialize fallocate with ext4_convert_unwritten_extents Fallocate should wait for pended ext4_convert_unwritten_extents() otherwise following race may happen: ftruncate( ,12288); fallocate( ,0, 4096) io_sibmit( ,0, 4096); /* Write to fallocated area, split extent if needed */ fallocate( ,0, 8192); /* Grow extent and broke assumption about extent */ Later kwork completion will do: ->ext4_convert_unwritten_extents (0, 4096) ->ext4_map_blocks(handle, inode, &map, EXT4_GET_BLOCKS_IO_CONVERT_EXT); ->ext4_ext_map_blocks() /* Will find new extent: ex = [0,2] !!!!!! */ ->ext4_ext_handle_uninitialized_extents() ->ext4_convert_unwritten_extents_endio() /* convert [0,2] extent to initialized, but only[0,1] was written */ Signed-off-by: Dmitry Monakhov Signed-off-by: "Theodore Ts'o" (cherry picked from commit 60d4616f3dc63371b3dc367e5e88fd4b4f037f65) --- fs/ext4/extents.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c index 37f46eb..ea2db86 100644 --- a/fs/ext4/extents.c +++ b/fs/ext4/extents.c @@ -4410,6 +4410,9 @@ long ext4_fallocate(struct file *file, int mode, loff_t offset, loff_t len) */ if (len <= EXT_UNINIT_MAX_LEN << blkbits) flags |= EXT4_GET_BLOCKS_NO_NORMALIZE; + + /* Prevent race condition between unwritten */ + ext4_flush_unwritten_io(inode); retry: while (ret >= 0 && ret < max_blocks) { map.m_lblk = map.m_lblk + ret; -- 1.7.12.rc0.22.gcdd159b