Re: [PATCH v3 4/6] ext4: reorder map.m_flags checks in ext4_iomap_begin()
From: Jan Kara <jack@suse.cz>
Date: 2019-09-23 15:08:45
Also in:
linux-fsdevel
On Thu 12-09-19 21:04:30, Matthew Bobrowski wrote:
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> Reviewed-by: Ritesh Harjani <redacted>
The patch looks good to me. You can add: Reviewed-by: Jan Kara <jack@suse.cz> Honza
quoted hunk ↗ jump to hunk
--- 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
-- Jan Kara [off-list ref] SUSE Labs, CR