[PATCH v3 03/16] iomap: refactor the writeback interface

Joanne Koong
2025-06-24T02:23:02Z

From: Christoph Hellwig <hch@lst.de>

Replace ->map_blocks with a new ->writeback_range, which differs in the
following ways:

- it must also queue up the I/O for writeback, that is called into the
slightly refactored and extended in scope iomap_add_to_ioend for
each region
- can handle only a part of the requested region, that is the retry
loop for partial mappings moves to the caller
- handles cleanup on failures as well, and thus also replaces the
discard_folio method only implemented by XFS.

This will allow to use the iomap writeback code also for file systems
that are not block based like fuse.

Co-developed-by: Joanne Koong <joannelkoong@gmail.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
---
.../filesystems/iomap/operations.rst | 23 +--
block/fops.c | 25 ++-
fs/gfs2/bmap.c | 26 +--
fs/iomap/buffered-io.c | 93 +++++------
fs/iomap/trace.h | 2 +-
fs/xfs/xfs_aops.c | 154 ++++++++++--------
fs/zonefs/file.c | 28 ++--
include/linux/iomap.h | 20 +--
8 files changed, 187 insertions(+), 184 deletions(-)

diff --git a/Documentation/filesystems/iomap/operations.rst b/Documentation/filesystems/iomap/operations.rst
index 3b628e370d88..b28f215db6e5 100644
--- a/Documentation/filesystems/iomap/operations.rst
+++ b/Documentation/filesystems/iomap/operations.rst
@@ -271,7 +271,7 @@ writeback.
It does not lock ``i_rwsem`` or ``invalidate_lock``.

The dirty bit will be cleared for all folios run through the
-``->map_blocks`` machinery described below even if the writeback fails.
+``->writeback_range`` machinery described below even if the writeback fails.
This is to prevent dirty folio clots when storage devices fail; an
``-EIO`` is recorded for userspace to collect via ``fsync``.

@@ -283,15 +283,14 @@ The ``ops`` structure must be specified and is as follows:
.. code-block:: c

struct iomap_writeback_ops {
- int (*map_blocks)(struct iomap_writepage_ctx *wpc, struct inode *inode,
- loff_t offset, unsigned len);
- int (*submit_ioend)(struct iomap_writepage_ctx *wpc, int status);
- void (*discard_folio)(struct folio *folio, loff_t pos);
+ int (*writeback_range)(struct iomap_writepage_ctx *wpc,
+ struct folio *folio, u64 pos, unsigned int len, u64 end_pos);
+ int (*submit_ioend)(struct iomap_writepage_ctx *wpc, int status);
};

The fields are as follows:

- - ``map_blocks``: Sets ``wpc->iomap`` to the space mapping of the file
+ - ``writeback_range``: Sets ``wpc->iomap`` to the space mapping of the file
range (in bytes) given by ``offset`` and ``len``.
iomap calls this function for each dirty fs block in each dirty folio,
though it will `reuse mappings
@@ -316,18 +315,6 @@ The fields are as follows:
transactions from process context before submitting the bio.
This function is optional.

- - ``discard_folio``: iomap calls this function after ``->map_blocks``
- fails to schedule I/O for any part of a dirty folio.
- The function should throw away any reservations that may have been
- made for the write.
- The folio will be marked clean and an ``-EIO`` recorded in the
- pagecache.
- Filesystems can use this callback to `remove
- <https://lore.kernel.org/all/20201029163313.1766967-1-bfoster@redhat.com/>`_
- delalloc reservations to avoid having delalloc reservations for
- clean pagecache.
- This function is optional.
-
Pagecache Writeback Completion
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

diff --git a/block/fops.c b/block/fops.c
index 3394263d942b..b500ff8f55dd 100644
--- a/block/fops.c
+++ b/block/fops.c
@@ -537,22 +537,29 @@ static void blkdev_readahead(struct readahead_control *rac)
iomap_readahead(rac, &blkdev_iomap_ops);
}

-static int blkdev_map_blocks(struct iomap_writepage_ctx *wpc,
- struct inode *inode, loff_t offset, unsigned int len)
+static ssize_t blkdev_writeback_range(struct iomap_writepage_ctx *wpc,
+ struct folio *folio, u64 offset, unsigned int len, u64 end_pos)
{
- loff_t isize = i_size_read(inode);
+ loff_t isize = i_size_read(wpc->inode);

if (WARN_ON_ONCE(offset >= isize))
return -EIO;
- if (offset >= wpc->iomap.offset &&
- offset < wpc->iomap.offset + wpc->iomap.length)
- return 0;
- return blkdev_iomap_begin(inode, offset, isize - offset,
- IOMAP_WRITE, &wpc->iomap, NULL);
+
+ if (offset < wpc->iomap.offset ||
+ offset >= wpc->iomap.offset + wpc->iomap.length) {
+ int error;
+
+ error = blkdev_iomap_begin(wpc->inode, offset, isize - offset,
+ IOMAP_WRITE, &wpc->iomap, NULL);
+ if (error)
+ return error;
+ }
+
+ return iomap_add_to_ioend(wpc, folio, offset, end_pos, len);
}

static const struct iomap_writeback_ops blkdev_writeback_ops = {
- .map_blocks = blkdev_map_blocks,
+ .writeback_range = blkdev_writeback_range,
};

static int blkdev_writepages(struct address_space *mapping,
diff --git a/fs/gfs2/bmap.c b/fs/gfs2/bmap.c
index 7703d0471139..0cc41de54aba 100644
--- a/fs/gfs2/bmap.c
+++ b/fs/gfs2/bmap.c
@@ -2469,23 +2469,25 @@ int __gfs2_punch_hole(struct file *file, loff_t offset, loff_t length)
return error;
}

-static int gfs2_map_blocks(struct iomap_writepage_ctx *wpc, struct inode *inode,
- loff_t offset, unsigned int len)
+static ssize_t gfs2_writeback_range(struct iomap_writepage_ctx *wpc,
+ struct folio *folio, u64 offset, unsigned int len, u64 end_pos)
{
- int ret;
-
- if (WARN_ON_ONCE(gfs2_is_stuffed(GFS2_I(inode))))
+ if (WARN_ON_ONCE(gfs2_is_stuffed(GFS2_I(wpc->inode))))
return -EIO;

- if (offset >= wpc->iomap.offset &&
- offset < wpc->iomap.offset + wpc->iomap.length)
- return 0;
+ if (offset < wpc->iomap.offset ||
+ offset >= wpc->iomap.offset + wpc->iomap.length) {
+ int ret;

- memset(&wpc->iomap, 0, sizeof(wpc->iomap));
- ret = gfs2_iomap_get(inode, offset, INT_MAX, &wpc->iomap);
- return ret;
+ memset(&wpc->iomap, 0, sizeof(wpc->iomap));
+ ret = gfs2_iomap_get(wpc->inode, offset, INT_MAX, &wpc->iomap);
+ if (ret)
+ return ret;
+ }
+
+ return iomap_add_to_ioend(wpc, folio, offset, end_pos, len);
}

const struct iomap_writeback_ops gfs2_writeback_ops = {
- .map_blocks = gfs2_map_blocks,
+ .writeback_range = gfs2_writeback_range,
};
diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index 11a55da26a6f..80d8acfaa068 100644
--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c
@@ -1676,14 +1676,30 @@ static bool iomap_can_add_to_ioend(struct iomap_writepage_ctx *wpc, loff_t pos,
* At the end of a writeback pass, there will be a cached ioend remaining on the
* writepage context that the caller will need to submit.
*/
-static int iomap_add_to_ioend(struct iomap_writepage_ctx *wpc,
- struct folio *folio, loff_t pos, loff_t end_pos, unsigned len)
+ssize_t iomap_add_to_ioend(struct iomap_writepage_ctx *wpc, struct folio *folio,
+ loff_t pos, loff_t end_pos, unsigned int dirty_len)
{
struct iomap_folio_state *ifs = folio->private;
size_t poff = offset_in_folio(folio, pos);
unsigned int ioend_flags = 0;
+ unsigned int map_len = min_t(u64, dirty_len,
+ wpc->iomap.offset + wpc->iomap.length - pos);
int error;

+ trace_iomap_add_to_ioend(wpc->inode, pos, dirty_len, &wpc->iomap);
+
+ WARN_ON_ONCE(!folio->private && map_len < dirty_len);
+
+ switch (wpc->iomap.type) {
+ case IOMAP_INLINE:
+ WARN_ON_ONCE(1);
+ return -EIO;
+ case IOMAP_HOLE:
+ return map_len;
+ default:
+ break;
+ }
+
if (wpc->iomap.type == IOMAP_UNWRITTEN)
ioend_flags |= IOMAP_IOEND_UNWRITTEN;
if (wpc->iomap.flags & IOMAP_F_SHARED)
@@ -1701,11 +1717,11 @@ static int iomap_add_to_ioend(struct iomap_writepage_ctx *wpc,
wpc->ioend = iomap_alloc_ioend(wpc, pos, ioend_flags);
}

- if (!bio_add_folio(&wpc->ioend->io_bio, folio, len, poff))
+ if (!bio_add_folio(&wpc->ioend->io_bio, folio, map_len, poff))
goto new_ioend;

if (ifs)
- atomic_add(len, &ifs->write_bytes_pending);
+ atomic_add(map_len, &ifs->write_bytes_pending);

/*
* Clamp io_offset and io_size to the incore EOF so that ondisk
@@ -1748,63 +1764,34 @@ static int iomap_add_to_ioend(struct iomap_writepage_ctx *wpc,
* Note that this defeats the ability to chain the ioends of
* appending writes.
*/
- wpc->ioend->io_size += len;
+ wpc->ioend->io_size += map_len;
if (wpc->ioend->io_offset + wpc->ioend->io_size > end_pos)
wpc->ioend->io_size = end_pos - wpc->ioend->io_offset;

- wbc_account_cgroup_owner(wpc->wbc, folio, len);
- return 0;
+ wbc_account_cgroup_owner(wpc->wbc, folio, map_len);
+ return map_len;
}
+EXPORT_SYMBOL_GPL(iomap_add_to_ioend);

-static int iomap_writepage_map_blocks(struct iomap_writepage_ctx *wpc,
- struct folio *folio, u64 pos, u64 end_pos, unsigned dirty_len,
+static int iomap_writeback_range(struct iomap_writepage_ctx *wpc,
+ struct folio *folio, u64 pos, u32 rlen, u64 end_pos,
bool *wb_pending)
{
- int error;
-
do {
- unsigned map_len;
-
- error = wpc->ops->map_blocks(wpc, wpc->inode, pos, dirty_len);
- if (error)
- break;
- trace_iomap_writepage_map(wpc->inode, pos, dirty_len,
- &wpc->iomap);
-
- map_len = min_t(u64, dirty_len,
- wpc->iomap.offset + wpc->iomap.length - pos);
- WARN_ON_ONCE(!folio->private && map_len < dirty_len);
+ ssize_t ret;

- switch (wpc->iomap.type) {
- case IOMAP_INLINE:
- WARN_ON_ONCE(1);
- error = -EIO;
- break;
- case IOMAP_HOLE:
- break;
- default:
- error = iomap_add_to_ioend(wpc, folio, pos, end_pos,
- map_len);
- if (!error)
- *wb_pending = true;
- break;
- }
- dirty_len -= map_len;
- pos += map_len;
- } while (dirty_len && !error);
+ ret = wpc->ops->writeback_range(wpc, folio, pos, rlen, end_pos);
+ if (WARN_ON_ONCE(ret == 0 || ret > rlen))
+ return -EIO;
+ if (ret < 0)
+ return ret;
+ rlen -= ret;
+ pos += ret;
+ if (wpc->iomap.type != IOMAP_HOLE)
+ *wb_pending = true;
+ } while (rlen);

- /*
- * We cannot cancel the ioend directly here on error. We may have
- * already set other pages under writeback and hence we have to run I/O
- * completion to mark the error state of the pages under writeback
- * appropriately.
- *
- * Just let the file system know what portion of the folio failed to
- * map.
- */
- if (error && wpc->ops->discard_folio)
- wpc->ops->discard_folio(folio, pos);
- return error;
+ return 0;
}

/*
@@ -1916,8 +1903,8 @@ static int iomap_writepage_map(struct iomap_writepage_ctx *wpc,
*/
end_aligned = round_up(end_pos, i_blocksize(inode));
while ((rlen = iomap_find_dirty_range(folio, &pos, end_aligned))) {
- error = iomap_writepage_map_blocks(wpc, folio, pos, end_pos,
- rlen, &wb_pending);
+ error = iomap_writeback_range(wpc, folio, pos, rlen, end_pos,
+ &wb_pending);
if (error)
break;
pos += rlen;
diff --git a/fs/iomap/trace.h b/fs/iomap/trace.h
index 455cc6f90be0..aaea02c9560a 100644
--- a/fs/iomap/trace.h
+++ b/fs/iomap/trace.h
@@ -169,7 +169,7 @@ DEFINE_EVENT(iomap_class, name, \
DEFINE_IOMAP_EVENT(iomap_iter_dstmap);
DEFINE_IOMAP_EVENT(iomap_iter_srcmap);

-TRACE_EVENT(iomap_writepage_map,
+TRACE_EVENT(iomap_add_to_ioend,
TP_PROTO(struct inode *inode, u64 pos, unsigned int dirty_len,
struct iomap *iomap),
TP_ARGS(inode, pos, dirty_len, iomap),
diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c
index 65485a52df3b..8157b6d92c8e 100644
--- a/fs/xfs/xfs_aops.c
+++ b/fs/xfs/xfs_aops.c
@@ -233,6 +233,47 @@ xfs_end_bio(
spin_unlock_irqrestore(&ip->i_ioend_lock, flags);
}

+/*
+ * We cannot cancel the ioend directly on error. We may have already set other
+ * pages under writeback and hence we have to run I/O completion to mark the
+ * error state of the pages under writeback appropriately.
+ *
+ * If the folio has delalloc blocks on it, the caller is asking us to punch them
+ * out. If we don't, we can leave a stale delalloc mapping covered by a clean
+ * page that needs to be dirtied again before the delalloc mapping can be
+ * converted. This stale delalloc mapping can trip up a later direct I/O read
+ * operation on the same region.
+ *
+ * We prevent this by truncating away the delalloc regions on the folio. Because
+ * they are delalloc, we can do this without needing a transaction. Indeed - if
+ * we get ENOSPC errors, we have to be able to do this truncation without a
+ * transaction as there is no space left for block reservation (typically why
+ * we see a ENOSPC in writeback).
+ */
+static void
+xfs_discard_folio(
+ struct folio *folio,
+ loff_t pos)
+{
+ struct xfs_inode *ip = XFS_I(folio->mapping->host);
+ struct xfs_mount *mp = ip->i_mount;
+
+ if (xfs_is_shutdown(mp))
+ return;
+
+ xfs_alert_ratelimited(mp,
+ "page discard on page "PTR_FMT", inode 0x%llx, pos %llu.",
+ folio, ip->i_ino, pos);
+
+ /*
+ * The end of the punch range is always the offset of the first
+ * byte of the next folio. Hence the end offset is only dependent on the
+ * folio itself and not the start offset that is passed in.
+ */
+ xfs_bmap_punch_delalloc_range(ip, XFS_DATA_FORK, pos,
+ folio_pos(folio) + folio_size(folio), NULL);
+}
+
/*
* Fast revalidation of the cached writeback mapping. Return true if the current
* mapping is valid, false otherwise.
@@ -275,16 +316,17 @@ xfs_imap_valid(
return true;
}

-static int
-xfs_map_blocks(
+static ssize_t
+xfs_writeback_range(
struct iomap_writepage_ctx *wpc,
- struct inode *inode,
- loff_t offset,
- unsigned int len)
+ struct folio *folio,
+ u64 offset,
+ unsigned int len,
+ u64 end_pos)
{
- struct xfs_inode *ip = XFS_I(inode);
+ struct xfs_inode *ip = XFS_I(wpc->inode);
struct xfs_mount *mp = ip->i_mount;
- ssize_t count = i_blocksize(inode);
+ ssize_t count = i_blocksize(wpc->inode);
xfs_fileoff_t offset_fsb = XFS_B_TO_FSBT(mp, offset);
xfs_fileoff_t end_fsb = XFS_B_TO_FSB(mp, offset + count);
xfs_fileoff_t cow_fsb;
@@ -292,7 +334,7 @@ xfs_map_blocks(
struct xfs_bmbt_irec imap;
struct xfs_iext_cursor icur;
int retries = 0;
- int error = 0;
+ ssize_t ret = 0;
unsigned int *seq;

if (xfs_is_shutdown(mp))
@@ -316,7 +358,7 @@ xfs_map_blocks(
* out that ensures that we always see the current value.
*/
if (xfs_imap_valid(wpc, ip, offset))
- return 0;
+ goto map_blocks;

/*
* If we don't have a valid map, now it's time to get a new one for this
@@ -351,7 +393,7 @@ xfs_map_blocks(
*/
if (xfs_imap_valid(wpc, ip, offset)) {
xfs_iunlock(ip, XFS_ILOCK_SHARED);
- return 0;
+ goto map_blocks;
}

/*
@@ -389,7 +431,12 @@ xfs_map_blocks(

xfs_bmbt_to_iomap(ip, &wpc->iomap, &imap, 0, 0, XFS_WPC(wpc)->data_seq);
trace_xfs_map_blocks_found(ip, offset, count, whichfork, &imap);
- return 0;
+map_blocks:
+ ret = iomap_add_to_ioend(wpc, folio, offset, end_pos, len);
+ if (ret < 0)
+ goto out_error;
+ return ret;
+
allocate_blocks:
/*
* Convert a dellalloc extent to a real one. The current page is held
@@ -402,9 +449,9 @@ xfs_map_blocks(
else
seq = &XFS_WPC(wpc)->data_seq;

- error = xfs_bmapi_convert_delalloc(ip, whichfork, offset,
- &wpc->iomap, seq);
- if (error) {
+ ret = xfs_bmapi_convert_delalloc(ip, whichfork, offset, &wpc->iomap,
+ seq);
+ if (ret) {
/*
* If we failed to find the extent in the COW fork we might have
* raced with a COW to data fork conversion or truncate.
@@ -412,10 +459,10 @@ xfs_map_blocks(
* the former case, but prevent additional retries to avoid
* looping forever for the latter case.
*/
- if (error == -EAGAIN && whichfork == XFS_COW_FORK && !retries++)
+ if (ret == -EAGAIN && whichfork == XFS_COW_FORK && !retries++)
goto retry;
- ASSERT(error != -EAGAIN);
- return error;
+ ASSERT(ret != -EAGAIN);
+ goto out_error;
}

/*
@@ -433,7 +480,11 @@ xfs_map_blocks(
ASSERT(wpc->iomap.offset <= offset);
ASSERT(wpc->iomap.offset + wpc->iomap.length > offset);
trace_xfs_map_blocks_alloc(ip, offset, count, whichfork, &imap);
- return 0;
+ goto map_blocks;
+
+out_error:
+ xfs_discard_folio(folio, offset);
+ return ret;
}

static bool
@@ -488,47 +539,9 @@ xfs_submit_ioend(
return 0;
}

-/*
- * If the folio has delalloc blocks on it, the caller is asking us to punch them
- * out. If we don't, we can leave a stale delalloc mapping covered by a clean
- * page that needs to be dirtied again before the delalloc mapping can be
- * converted. This stale delalloc mapping can trip up a later direct I/O read
- * operation on the same region.
- *
- * We prevent this by truncating away the delalloc regions on the folio. Because
- * they are delalloc, we can do this without needing a transaction. Indeed - if
- * we get ENOSPC errors, we have to be able to do this truncation without a
- * transaction as there is no space left for block reservation (typically why
- * we see a ENOSPC in writeback).
- */
-static void
-xfs_discard_folio(
- struct folio *folio,
- loff_t pos)
-{
- struct xfs_inode *ip = XFS_I(folio->mapping->host);
- struct xfs_mount *mp = ip->i_mount;
-
- if (xfs_is_shutdown(mp))
- return;
-
- xfs_alert_ratelimited(mp,
- "page discard on page "PTR_FMT", inode 0x%llx, pos %llu.",
- folio, ip->i_ino, pos);
-
- /*
- * The end of the punch range is always the offset of the first
- * byte of the next folio. Hence the end offset is only dependent on the
- * folio itself and not the start offset that is passed in.
- */
- xfs_bmap_punch_delalloc_range(ip, XFS_DATA_FORK, pos,
- folio_pos(folio) + folio_size(folio), NULL);
-}
-
static const struct iomap_writeback_ops xfs_writeback_ops = {
- .map_blocks = xfs_map_blocks,
+ .writeback_range = xfs_writeback_range,
.submit_ioend = xfs_submit_ioend,
- .discard_folio = xfs_discard_folio,
};

struct xfs_zoned_writepage_ctx {
@@ -542,20 +555,22 @@ XFS_ZWPC(struct iomap_writepage_ctx *ctx)
return container_of(ctx, struct xfs_zoned_writepage_ctx, ctx);
}

-static int
-xfs_zoned_map_blocks(
+static ssize_t
+xfs_zoned_writeback_range(
struct iomap_writepage_ctx *wpc,
- struct inode *inode,
- loff_t offset,
- unsigned int len)
+ struct folio *folio,
+ u64 offset,
+ unsigned int len,
+ u64 end_pos)
{
- struct xfs_inode *ip = XFS_I(inode);
+ struct xfs_inode *ip = XFS_I(wpc->inode);
struct xfs_mount *mp = ip->i_mount;
xfs_fileoff_t offset_fsb = XFS_B_TO_FSBT(mp, offset);
xfs_fileoff_t end_fsb = XFS_B_TO_FSB(mp, offset + len);
xfs_filblks_t count_fsb;
struct xfs_bmbt_irec imap, del;
struct xfs_iext_cursor icur;
+ ssize_t ret;

if (xfs_is_shutdown(mp))
return -EIO;
@@ -586,7 +601,7 @@ xfs_zoned_map_blocks(
imap.br_state = XFS_EXT_NORM;
xfs_iunlock(ip, XFS_ILOCK_EXCL);
xfs_bmbt_to_iomap(ip, &wpc->iomap, &imap, 0, 0, 0);
- return 0;
+ goto map_blocks;
}
end_fsb = min(end_fsb, imap.br_startoff + imap.br_blockcount);
count_fsb = end_fsb - offset_fsb;
@@ -603,9 +618,13 @@ xfs_zoned_map_blocks(
wpc->iomap.offset = offset;
wpc->iomap.length = XFS_FSB_TO_B(mp, count_fsb);
wpc->iomap.flags = IOMAP_F_ANON_WRITE;
-
trace_xfs_zoned_map_blocks(ip, offset, wpc->iomap.length);
- return 0;
+
+map_blocks:
+ ret = iomap_add_to_ioend(wpc, folio, offset, end_pos, len);
+ if (ret < 0)
+ xfs_discard_folio(folio, offset);
+ return ret;
}

static int
@@ -621,9 +640,8 @@ xfs_zoned_submit_ioend(
}

static const struct iomap_writeback_ops xfs_zoned_writeback_ops = {
- .map_blocks = xfs_zoned_map_blocks,
+ .writeback_range = xfs_zoned_writeback_range,
.submit_ioend = xfs_zoned_submit_ioend,
- .discard_folio = xfs_discard_folio,
};

STATIC int
diff --git a/fs/zonefs/file.c b/fs/zonefs/file.c
index edca4bbe4b72..c88e2c851753 100644
--- a/fs/zonefs/file.c
+++ b/fs/zonefs/file.c
@@ -124,29 +124,33 @@ static void zonefs_readahead(struct readahead_control *rac)
* Map blocks for page writeback. This is used only on conventional zone files,
* which implies that the page range can only be within the fixed inode size.
*/
-static int zonefs_write_map_blocks(struct iomap_writepage_ctx *wpc,
- struct inode *inode, loff_t offset,
- unsigned int len)
+static ssize_t zonefs_writeback_range(struct iomap_writepage_ctx *wpc,
+ struct folio *folio, u64 offset, unsigned len, u64 end_pos)
{
- struct zonefs_zone *z = zonefs_inode_zone(inode);
+ struct zonefs_zone *z = zonefs_inode_zone(wpc->inode);

if (WARN_ON_ONCE(zonefs_zone_is_seq(z)))
return -EIO;
- if (WARN_ON_ONCE(offset >= i_size_read(inode)))
+ if (WARN_ON_ONCE(offset >= i_size_read(wpc->inode)))
return -EIO;

/* If the mapping is already OK, nothing needs to be done */
- if (offset >= wpc->iomap.offset &&
- offset < wpc->iomap.offset + wpc->iomap.length)
- return 0;
+ if (offset < wpc->iomap.offset ||
+ offset >= wpc->iomap.offset + wpc->iomap.length) {
+ int error;
+
+ error = zonefs_write_iomap_begin(wpc->inode, offset,
+ z->z_capacity - offset, IOMAP_WRITE,
+ &wpc->iomap, NULL);
+ if (error)
+ return error;
+ }

- return zonefs_write_iomap_begin(inode, offset,
- z->z_capacity - offset,
- IOMAP_WRITE, &wpc->iomap, NULL);
+ return iomap_add_to_ioend(wpc, folio, offset, end_pos, len);
}

static const struct iomap_writeback_ops zonefs_writeback_ops = {
- .map_blocks = zonefs_write_map_blocks,
+ .writeback_range = zonefs_writeback_range,
};

static int zonefs_writepages(struct address_space *mapping,
diff --git a/include/linux/iomap.h b/include/linux/iomap.h
index 00179c9387c5..063e18476286 100644
--- a/include/linux/iomap.h
+++ b/include/linux/iomap.h
@@ -416,18 +416,20 @@ static inline struct iomap_ioend *iomap_ioend_from_bio(struct bio *bio)

struct iomap_writeback_ops {
/*
- * Required, maps the blocks so that writeback can be performed on
- * the range starting at offset.
+ * Required, performs writeback on the passed in range
*
- * Can return arbitrarily large regions, but we need to call into it at
+ * Can map arbitrarily large regions, but we need to call into it at
* least once per folio to allow the file systems to synchronize with
* the write path that could be invalidating mappings.
*
* An existing mapping from a previous call to this method can be reused
* by the file system if it is still valid.
+ *
+ * Returns the number of bytes processed or a negative errno.
*/
- int (*map_blocks)(struct iomap_writepage_ctx *wpc, struct inode *inode,
- loff_t offset, unsigned len);
+ ssize_t (*writeback_range)(struct iomap_writepage_ctx *wpc,
+ struct folio *folio, u64 pos, unsigned int len,
+ u64 end_pos);

/*
* Optional, allows the file systems to hook into bio submission,
@@ -438,12 +440,6 @@ struct iomap_writeback_ops {
* the bio could not be submitted.
*/
int (*submit_ioend)(struct iomap_writepage_ctx *wpc, int status);
-
- /*
- * Optional, allows the file system to discard state on a page where
- * we failed to submit any I/O.
- */
- void (*discard_folio)(struct folio *folio, loff_t pos);
};

struct iomap_writepage_ctx {
@@ -463,6 +459,8 @@ void iomap_finish_ioends(struct iomap_ioend *ioend, int error);
void iomap_ioend_try_merge(struct iomap_ioend *ioend,
struct list_head *more_ioends);
void iomap_sort_ioends(struct list_head *ioend_list);
+ssize_t iomap_add_to_ioend(struct iomap_writepage_ctx *wpc, struct folio *folio,
+ loff_t pos, loff_t end_pos, unsigned int dirty_len);
int iomap_writepages(struct iomap_writepage_ctx *wpc);

/*
--
2.47.1