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Date: Tue, 5 Nov 2019 07:43:47 -0800
From: "Darrick J. Wong" <darrick.wong@...cle.com>
To: Matthew Bobrowski <mbobrowski@...browski.org>
Cc: tytso@....edu, jack@...e.cz, adilger.kernel@...ger.ca,
linux-ext4@...r.kernel.org, linux-fsdevel@...r.kernel.org,
riteshh@...ux.ibm.com
Subject: Re: [PATCH v7 06/11] ext4: introduce new callback for IOMAP_REPORT
On Tue, Nov 05, 2019 at 11:03:31PM +1100, Matthew Bobrowski wrote:
> As part of the ext4_iomap_begin() cleanups that precede this patch, we
> also split up the IOMAP_REPORT branch into a completely separate
> ->iomap_begin() callback named ext4_iomap_begin_report(). Again, the
> raionale for this change is to reduce the overall clutter within
> ext4_iomap_begin().
>
> Signed-off-by: Matthew Bobrowski <mbobrowski@...browski.org>
> Reviewed-by: Jan Kara <jack@...e.cz>
> Reviewed-by: Ritesh Harjani <riteshh@...ux.ibm.com>
> ---
> fs/ext4/ext4.h | 1 +
> fs/ext4/file.c | 6 ++-
> fs/ext4/inode.c | 134 +++++++++++++++++++++++++++++-------------------
> 3 files changed, 85 insertions(+), 56 deletions(-)
>
> diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
> index 3616f1b0c987..5c6c4acea8b1 100644
> --- a/fs/ext4/ext4.h
> +++ b/fs/ext4/ext4.h
> @@ -3388,6 +3388,7 @@ 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 b540f2903faa..b5ba6767b276 100644
> --- a/fs/ext4/inode.c
> +++ b/fs/ext4/inode.c
> @@ -3553,74 +3553,32 @@ static int ext4_iomap_alloc(struct inode *inode, struct ext4_map_blocks *map,
> static int ext4_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
> unsigned flags, struct iomap *iomap, struct iomap *srcmap)
> {
> - 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;
>
> 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 (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;
> - }
>
> - 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 (WARN_ON_ONCE(ext4_has_inline_data(inode)))
> + return -ERANGE;
>
> - 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;
> + /*
> + * Calculate the first and last logical blocks respectively.
> + */
> + map.m_lblk = offset >> blkbits;
> + map.m_len = min_t(loff_t, (offset + length - 1) >> blkbits,
> + EXT4_MAX_LOGICAL_BLOCK) - map.m_lblk + 1;
>
> - 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, &map, flags);
FWIW you could even split non-buffered read and write into separate iomap
ops and avoid this split... but that's a cleanup that can wait until
after the main series lands.
> - } else {
> + else
> ret = ext4_map_blocks(NULL, inode, &map, 0);
> - }
>
> if (ret < 0)
> return ret;
>
> ext4_set_iomap(inode, iomap, &map, offset, length);
> - if (delalloc && iomap->type == IOMAP_HOLE)
> - iomap->type = IOMAP_DELALLOC;
>
> return 0;
> }
> @@ -3682,6 +3640,74 @@ const struct iomap_ops ext4_iomap_ops = {
> .iomap_end = ext4_iomap_end,
> };
>
> +static bool ext4_iomap_is_delalloc(struct inode *inode,
> + struct ext4_map_blocks *map)
> +{
> + struct extent_status es;
> + ext4_lblk_t offset = 0, end = map->m_lblk + map->m_len - 1;
> +
> + ext4_es_find_extent_range(inode, &ext4_es_is_delayed,
> + map->m_lblk, end, &es);
> +
> + if (!es.es_len || es.es_lblk > end)
> + return false;
> +
> + if (es.es_lblk > map->m_lblk) {
> + map->m_len = es.es_lblk - map->m_lblk;
> + return false;
> + }
> +
> + offset = map->m_lblk - es.es_lblk;
> + map->m_len = es.es_len - offset;
> +
> + return true;
> +}
> +
> +static int ext4_iomap_begin_report(struct inode *inode, loff_t offset,
> + loff_t length, unsigned int flags,
> + struct iomap *iomap, struct iomap *srcmap)
> +{
> + int ret;
> + bool delalloc = false;
> + struct ext4_map_blocks map;
> + u8 blkbits = inode->i_blkbits;
> +
> + if ((offset >> blkbits) > EXT4_MAX_LOGICAL_BLOCK)
> + return -EINVAL;
> +
> + 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;
> + }
> + }
> +
> + /*
> + * Calculate the first and last logical block respectively.
> + */
> + map.m_lblk = offset >> blkbits;
> + map.m_len = min_t(loff_t, (offset + length - 1) >> blkbits,
> + EXT4_MAX_LOGICAL_BLOCK) - map.m_lblk + 1;
> +
> + ret = ext4_map_blocks(NULL, inode, &map, 0);
> + if (ret < 0)
> + return ret;
> + if (ret == 0)
> + delalloc = ext4_iomap_is_delalloc(inode, &map);
If you can tell that a mapping is delalloc from @inode and @map, how
about pushing the ext4_iomap_is_delalloc call into ext4_set_iomap?
Oh, humm, the _is_delalloc function isn't a predicate after all; it
modifies @map. Urrk.
--D
> +
> + ext4_set_iomap(inode, iomap, &map, offset, length);
> + if (delalloc && iomap->type == IOMAP_HOLE)
> + iomap->type = IOMAP_DELALLOC;
> +
> + return 0;
> +}
> +
> +const struct iomap_ops ext4_iomap_report_ops = {
> + .iomap_begin = ext4_iomap_begin_report,
> +};
> +
> static int ext4_end_io_dio(struct kiocb *iocb, loff_t offset,
> ssize_t size, void *private)
> {
> --
> 2.20.1
>
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