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Message-Id: <20191009060022.4878542049@d06av24.portsmouth.uk.ibm.com>
Date: Wed, 9 Oct 2019 11:30:21 +0530
From: Ritesh Harjani <riteshh@...ux.ibm.com>
To: Matthew Bobrowski <mbobrowski@...browski.org>, tytso@....edu,
jack@...e.cz, adilger.kernel@...ger.ca
Cc: linux-ext4@...r.kernel.org, linux-fsdevel@...r.kernel.org,
hch@...radead.org, david@...morbit.com, darrick.wong@...cle.com,
riteshh@...ux.ibm.com
Subject: Re: [PATCH v4 3/8] ext4: introduce new callback for IOMAP_REPORT
operations
On 10/3/19 5:03 PM, Matthew Bobrowski wrote:
> As part of ext4_iomap_begin() cleanups and port across direct I/O path
> to make use of iomap infrastructure, we split IOMAP_REPORT operations
> into a separate ->iomap_begin() handler.
>
> Signed-off-by: Matthew Bobrowski <mbobrowski@...browski.org>
> ---
> fs/ext4/ext4.h | 1 +
> fs/ext4/file.c | 6 ++-
> fs/ext4/inode.c | 129 ++++++++++++++++++++++++++++--------------------
> 3 files changed, 80 insertions(+), 56 deletions(-)
>
> diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
> index 03db3e71676c..d0d88f411a44 100644
> --- a/fs/ext4/ext4.h
> +++ b/fs/ext4/ext4.h
> @@ -3379,6 +3379,7 @@ static inline void ext4_clear_io_unwritten_flag(ext4_io_end_t *io_end)
> }
>
> extern const struct iomap_ops ext4_iomap_ops;
> +extern const struct iomap_ops ext4_iomap_report_ops;
>
> static inline int ext4_buffer_uptodate(struct buffer_head *bh)
> {
> diff --git a/fs/ext4/file.c b/fs/ext4/file.c
> index 8d2bbcc2d813..ab75aee3e687 100644
> --- a/fs/ext4/file.c
> +++ b/fs/ext4/file.c
> @@ -494,12 +494,14 @@ loff_t ext4_llseek(struct file *file, loff_t offset, int whence)
> maxbytes, i_size_read(inode));
> case SEEK_HOLE:
> inode_lock_shared(inode);
> - offset = iomap_seek_hole(inode, offset, &ext4_iomap_ops);
> + offset = iomap_seek_hole(inode, offset,
> + &ext4_iomap_report_ops);
> inode_unlock_shared(inode);
> break;
> case SEEK_DATA:
> inode_lock_shared(inode);
> - offset = iomap_seek_data(inode, offset, &ext4_iomap_ops);
> + offset = iomap_seek_data(inode, offset,
> + &ext4_iomap_report_ops);
> inode_unlock_shared(inode);
> break;
> }
> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> index caeb3dec0dec..1dace576b8bd 100644
> --- a/fs/ext4/inode.c
> +++ b/fs/ext4/inode.c
> @@ -3439,6 +3439,72 @@ static int ext4_set_iomap(struct inode *inode, struct iomap *iomap, u16 type,
> return 0;
> }
>
> +static u16 ext4_iomap_check_delalloc(struct inode *inode,
> + struct ext4_map_blocks *map)
> +{
> + struct extent_status es;
> + ext4_lblk_t end = map->m_lblk + map->m_len - 1;
> +
> + ext4_es_find_extent_range(inode, &ext4_es_is_delayed, map->m_lblk,
> + end, &es);
> +
> + /* Entire range is a hole */
> + if (!es.es_len || es.es_lblk > end)
> + return IOMAP_HOLE;
> + if (es.es_lblk <= map->m_lblk) {
> + ext4_lblk_t offset = 0;
> +
> + if (es.es_lblk < map->m_lblk)
> + offset = map->m_lblk - es.es_lblk;
> + map->m_lblk = es.es_lblk + offset;
This looks redundant no? map->m_lblk never changes actually.
So this is not needed here.
> + map->m_len = es.es_len - offset;
> + return IOMAP_DELALLOC;
> + }
> +
> + /* Range starts with a hole */
> + map->m_len = es.es_lblk - map->m_lblk;
> + return IOMAP_HOLE;
> +}
> +
> +static int ext4_iomap_begin_report(struct inode *inode, loff_t offset,
> + loff_t length, unsigned flags,
> + struct iomap *iomap)
> +{
> + int ret;
> + u16 type = 0;
> + struct ext4_map_blocks map;
> + u8 blkbits = inode->i_blkbits;
> + unsigned long first_block, last_block;
> +
> + if ((offset >> blkbits) > EXT4_MAX_LOGICAL_BLOCK)
> + return -EINVAL;
> + first_block = offset >> blkbits;
> + last_block = min_t(loff_t, (offset + length - 1) >> blkbits,
> + EXT4_MAX_LOGICAL_BLOCK);
> +
> + if (ext4_has_inline_data(inode)) {
> + ret = ext4_inline_data_iomap(inode, iomap);
> + if (ret != -EAGAIN) {
> + if (ret == 0 && offset >= iomap->length)
> + ret = -ENOENT;
> + return ret;
> + }
> + }
> +
> + map.m_lblk = first_block;
> + map.m_len = last_block = first_block + 1;
> + ret = ext4_map_blocks(NULL, inode, &map, 0);
> + if (ret < 0)
> + return ret;
> + if (ret == 0)
> + type = ext4_iomap_check_delalloc(inode, &map);
> + return ext4_set_iomap(inode, iomap, type, first_block, &map);
We don't need to send first_block here. Since map->m_lblk
is same as first_block.
Also with Jan comment, we don't even need 'type' parameter.
Then we should be able to rename the function
ext4_set_iomap ==> ext4_map_to_iomap. This better reflects what it is
doing. Thoughts?
> +}
> +
> +const struct iomap_ops ext4_iomap_report_ops = {
> + .iomap_begin = ext4_iomap_begin_report,
> +};
> +
> static int ext4_iomap_alloc(struct inode *inode,
> unsigned flags,
> unsigned long first_block,
> @@ -3498,12 +3564,10 @@ static int ext4_iomap_alloc(struct inode *inode,
> static int ext4_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
> unsigned flags, struct iomap *iomap)
> {
> - u16 type = 0;
> - unsigned int blkbits = inode->i_blkbits;
> - unsigned long first_block, last_block;
> - struct ext4_map_blocks map;
> - bool delalloc = false;
> int ret;
> + struct ext4_map_blocks map;
> + u8 blkbits = inode->i_blkbits;
> + unsigned long first_block, last_block;
>
> if ((offset >> blkbits) > EXT4_MAX_LOGICAL_BLOCK)
> return -EINVAL;
> @@ -3511,64 +3575,21 @@ static int ext4_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
> last_block = min_t(loff_t, (offset + length - 1) >> blkbits,
> EXT4_MAX_LOGICAL_BLOCK);
>
> - if (flags & IOMAP_REPORT) {
> - if (ext4_has_inline_data(inode)) {
> - ret = ext4_inline_data_iomap(inode, iomap);
> - if (ret != -EAGAIN) {
> - if (ret == 0 && offset >= iomap->length)
> - ret = -ENOENT;
> - return ret;
> - }
> - }
> - } else {
> - if (WARN_ON_ONCE(ext4_has_inline_data(inode)))
> - return -ERANGE;
> - }
> + if (WARN_ON_ONCE(ext4_has_inline_data(inode)))
> + return -ERANGE;
>
> map.m_lblk = first_block;
> map.m_len = last_block - first_block + 1;
>
> - if (flags & IOMAP_REPORT) {
> - ret = ext4_map_blocks(NULL, inode, &map, 0);
> - if (ret < 0)
> - return ret;
> -
> - if (ret == 0) {
> - ext4_lblk_t end = map.m_lblk + map.m_len - 1;
> - struct extent_status es;
> -
> - ext4_es_find_extent_range(inode, &ext4_es_is_delayed,
> - map.m_lblk, end, &es);
> -
> - if (!es.es_len || es.es_lblk > end) {
> - /* entire range is a hole */
> - } else if (es.es_lblk > map.m_lblk) {
> - /* range starts with a hole */
> - map.m_len = es.es_lblk - map.m_lblk;
> - } else {
> - ext4_lblk_t offs = 0;
> -
> - if (es.es_lblk < map.m_lblk)
> - offs = map.m_lblk - es.es_lblk;
> - map.m_lblk = es.es_lblk + offs;
> - map.m_len = es.es_len - offs;
> - delalloc = true;
> - }
> - }
> - } else if (flags & IOMAP_WRITE) {
> + if (flags & IOMAP_WRITE)
> ret = ext4_iomap_alloc(inode, flags, first_block, &map);
> - } else {
> + else
> ret = ext4_map_blocks(NULL, inode, &map, 0);
> - if (ret < 0)
> - return ret;
> - }
>
> if (ret < 0)
> return ret;
> -
> - if (!ret)
> - type = delalloc ? IOMAP_DELALLOC : IOMAP_HOLE;
> - return ext4_set_iomap(inode, iomap, type, first_block, &map);
> + return ext4_set_iomap(inode, iomap, ret ? 0 : IOMAP_HOLE, first_block,
> + &map);
> }
>
> static int ext4_iomap_end(struct inode *inode, loff_t offset, loff_t length,
>
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