diff mbox series

[v4,7/8] ext4: reorder map.m_flags checks in ext4_set_iomap()

Message ID 3551610e53aa1984210a4de04ad6e1a89f5bf0a3.1570100361.git.mbobrowski@mbobrowski.org (mailing list archive)
State New, archived
Headers show
Series ext4: port direct I/O to iomap infrastructure | expand

Commit Message

Matthew Bobrowski Oct. 3, 2019, 11:34 a.m. UTC 
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 <mbobrowski@mbobrowski.org>
---
 fs/ext4/inode.c | 16 +++++++++++++---
 1 file changed, 13 insertions(+), 3 deletions(-)

Comments

Jan Kara Oct. 8, 2019, 11:30 a.m. UTC | #1 
On Thu 03-10-19 21:34:51, 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 <mbobrowski@mbobrowski.org>

The patch looks good to me. You can add:

Reviewed-by: Jan Kara <jack@suse.cz>

Just those 72 columns limited comment lines... ;)

								Honza

> ---
>  fs/ext4/inode.c | 16 +++++++++++++---
>  1 file changed, 13 insertions(+), 3 deletions(-)
> 
> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> index e133dda55063..63ad23ae05b8 100644
> --- a/fs/ext4/inode.c
> +++ b/fs/ext4/inode.c
> @@ -3420,10 +3420,20 @@ static int ext4_set_iomap(struct inode *inode, struct iomap *iomap, u16 type,
>  		iomap->type = type;
>  		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 I/O
> +		 * writes can result in map->m_flags having both
> +		 * EXT4_MAP_MAPPED and EXT4_MAP_UNWRITTEN bits set. In
> +		 * order for allocated extents to be converted to
> +		 * written extents in the ->end_io handler correctly,
> +		 * we need to ensure that the iomap->type is set
> +		 * approprately. 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
>
Ritesh Harjani Oct. 9, 2019, 6:35 a.m. UTC | #2 
On 10/3/19 5:04 PM, 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 <mbobrowski@mbobrowski.org>

You may be changing the function parameters & name here,
(in ext4_set_iomap)
But functionality wise the patch looks good to me.

You may add:
Reviewed-by: Ritesh Harjani <riteshh@linux.ibm.com>


> ---
>   fs/ext4/inode.c | 16 +++++++++++++---
>   1 file changed, 13 insertions(+), 3 deletions(-)
> 
> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> index e133dda55063..63ad23ae05b8 100644
> --- a/fs/ext4/inode.c
> +++ b/fs/ext4/inode.c
> @@ -3420,10 +3420,20 @@ static int ext4_set_iomap(struct inode *inode, struct iomap *iomap, u16 type,
>   		iomap->type = type;
>   		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 I/O
> +		 * writes can result in map->m_flags having both
> +		 * EXT4_MAP_MAPPED and EXT4_MAP_UNWRITTEN bits set. In
> +		 * order for allocated extents to be converted to
> +		 * written extents in the ->end_io handler correctly,
> +		 * we need to ensure that the iomap->type is set
> +		 * approprately. 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;
>
Matthew Bobrowski Oct. 9, 2019, 10:42 a.m. UTC | #3 
On Tue, Oct 08, 2019 at 01:30:12PM +0200, Jan Kara wrote:
> The patch looks good to me. You can add:
> 
> Reviewed-by: Jan Kara <jack@suse.cz>

Thanks Jan!

> Just those 72 columns limited comment lines... ;)

*nod* - will be fixed!

--<M>--
Matthew Bobrowski Oct. 9, 2019, 10:43 a.m. UTC | #4 
On Wed, Oct 09, 2019 at 12:05:47PM +0530, Ritesh Harjani wrote:
> You may be changing the function parameters & name here,
> (in ext4_set_iomap)

Hm, maybe. :P It all depends on the outcome of what we discuss in 1/8.

> But functionality wise the patch looks good to me.
> 
> You may add:
> Reviewed-by: Ritesh Harjani <riteshh@linux.ibm.com>

Great, thanks Ritesh!

--<M>--
diff mbox series

Patch

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index e133dda55063..63ad23ae05b8 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -3420,10 +3420,20 @@  static int ext4_set_iomap(struct inode *inode, struct iomap *iomap, u16 type,
 		iomap->type = type;
 		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 I/O
+		 * writes can result in map->m_flags having both
+		 * EXT4_MAP_MAPPED and EXT4_MAP_UNWRITTEN bits set. In
+		 * order for allocated extents to be converted to
+		 * written extents in the ->end_io handler correctly,
+		 * we need to ensure that the iomap->type is set
+		 * approprately. 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;