[PATCH v2 4/6] ext4: reorder map.m_flags checks in ext4_iomap_begin()
From: Matthew Bobrowski <hidden>
Date: 2019-09-08 23:19:52
Also in:
linux-fsdevel
Subsystem:
ext4 file system, filesystems (vfs and infrastructure), the rest · Maintainers:
"Theodore Ts'o", Alexander Viro, Christian Brauner, Linus Torvalds
For iomap direct IO write code path changes, we need to accommodate for the case where the block mapping flags passed to ext4_map_blocks() will result in m_flags having both EXT4_MAP_MAPPED and EXT4_MAP_UNWRITTEN bits set. In order for the allocated unwritten extents to be converted properly in the end_io handler, iomap->type must be set to IOMAP_UNWRITTEN, so we need to reshuffle the conditional statement in order to achieve this. This change is a no-op for DAX code path as the block mapping flag passed to ext4_map_blocks() when IS_DAX(inode) never results in EXT4_MAP_MAPPED and EXT4_MAP_UNWRITTEN being set at once. Signed-off-by: Matthew Bobrowski <redacted> --- fs/ext4/inode.c | 17 ++++++++++++++--- 1 file changed, 14 insertions(+), 3 deletions(-)
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 761ce6286b05..efb184928e51 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c@@ -3581,10 +3581,21 @@ static int ext4_iomap_begin(struct inode *inode, loff_t offset, loff_t length, iomap->type = delalloc ? IOMAP_DELALLOC : IOMAP_HOLE; iomap->addr = IOMAP_NULL_ADDR; } else { - if (map.m_flags & EXT4_MAP_MAPPED) { - iomap->type = IOMAP_MAPPED; - } else if (map.m_flags & EXT4_MAP_UNWRITTEN) { + /* + * Flags passed to ext4_map_blocks() for direct IO + * writes can result in m_flags having both + * EXT4_MAP_MAPPED and EXT4_MAP_UNWRITTEN bits set. In + * order for allocated unwritten extents to be + * converted to written extents in the end_io handler + * correctly, we need to ensure that the iomap->type + * is also set appropriately in that case. Thus, we + * need to check whether EXT4_MAP_UNWRITTEN is set + * first. + */ + if (map.m_flags & EXT4_MAP_UNWRITTEN) { iomap->type = IOMAP_UNWRITTEN; + } else if (map.m_flags & EXT4_MAP_MAPPED) { + iomap->type = IOMAP_MAPPED; } else { WARN_ON_ONCE(1); return -EIO;
--
2.20.1