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Subject[PATCH v2 9/9] iomap: Change calling convention for zeroing
Date
Pass the full length to iomap_zero() and dax_iomap_zero(), and have
them return how many bytes they actually handled. This is preparatory
work for handling THP, although it looks like DAX could actually take
advantage of it if there's a larger contiguous area.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
fs/dax.c | 13 ++++++-------
fs/iomap/buffered-io.c | 33 +++++++++++++++------------------
include/linux/dax.h | 3 +--
3 files changed, 22 insertions(+), 27 deletions(-)

diff --git a/fs/dax.c b/fs/dax.c
index 994ab66a9907..6ad346352a8c 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -1037,18 +1037,18 @@ static vm_fault_t dax_load_hole(struct xa_state *xas,
return ret;
}

-int dax_iomap_zero(loff_t pos, unsigned offset, unsigned size,
- struct iomap *iomap)
+s64 dax_iomap_zero(loff_t pos, u64 length, struct iomap *iomap)
{
sector_t sector = iomap_sector(iomap, pos & PAGE_MASK);
pgoff_t pgoff;
long rc, id;
void *kaddr;
bool page_aligned = false;
-
+ unsigned offset = offset_in_page(pos);
+ unsigned size = min_t(u64, PAGE_SIZE - offset, length);

if (IS_ALIGNED(sector << SECTOR_SHIFT, PAGE_SIZE) &&
- IS_ALIGNED(size, PAGE_SIZE))
+ (size == PAGE_SIZE))
page_aligned = true;

rc = bdev_dax_pgoff(iomap->bdev, sector, PAGE_SIZE, &pgoff);
@@ -1058,8 +1058,7 @@ int dax_iomap_zero(loff_t pos, unsigned offset, unsigned size,
id = dax_read_lock();

if (page_aligned)
- rc = dax_zero_page_range(iomap->dax_dev, pgoff,
- size >> PAGE_SHIFT);
+ rc = dax_zero_page_range(iomap->dax_dev, pgoff, 1);
else
rc = dax_direct_access(iomap->dax_dev, pgoff, 1, &kaddr, NULL);
if (rc < 0) {
@@ -1072,7 +1071,7 @@ int dax_iomap_zero(loff_t pos, unsigned offset, unsigned size,
dax_flush(iomap->dax_dev, kaddr + offset, size);
}
dax_read_unlock(id);
- return 0;
+ return size;
}

static loff_t
diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index cb25a7b70401..3e1eb40a73fd 100644
--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c
@@ -898,11 +898,13 @@ iomap_file_unshare(struct inode *inode, loff_t pos, loff_t len,
}
EXPORT_SYMBOL_GPL(iomap_file_unshare);

-static int iomap_zero(struct inode *inode, loff_t pos, unsigned offset,
- unsigned bytes, struct iomap *iomap, struct iomap *srcmap)
+static s64 iomap_zero(struct inode *inode, loff_t pos, u64 length,
+ struct iomap *iomap, struct iomap *srcmap)
{
struct page *page;
int status;
+ unsigned offset = offset_in_page(pos);
+ unsigned bytes = min_t(u64, PAGE_SIZE - offset, length);

status = iomap_write_begin(inode, pos, bytes, 0, &page, iomap, srcmap);
if (status)
@@ -914,38 +916,33 @@ static int iomap_zero(struct inode *inode, loff_t pos, unsigned offset,
return iomap_write_end(inode, pos, bytes, bytes, page, iomap, srcmap);
}

-static loff_t
-iomap_zero_range_actor(struct inode *inode, loff_t pos, loff_t count,
- void *data, struct iomap *iomap, struct iomap *srcmap)
+static loff_t iomap_zero_range_actor(struct inode *inode, loff_t pos,
+ loff_t length, void *data, struct iomap *iomap,
+ struct iomap *srcmap)
{
bool *did_zero = data;
loff_t written = 0;
- int status;

/* already zeroed? we're done. */
if (srcmap->type == IOMAP_HOLE || srcmap->type == IOMAP_UNWRITTEN)
- return count;
+ return length;

do {
- unsigned offset, bytes;
-
- offset = offset_in_page(pos);
- bytes = min_t(loff_t, PAGE_SIZE - offset, count);
+ s64 bytes;

if (IS_DAX(inode))
- status = dax_iomap_zero(pos, offset, bytes, iomap);
+ bytes = dax_iomap_zero(pos, length, iomap);
else
- status = iomap_zero(inode, pos, offset, bytes, iomap,
- srcmap);
- if (status < 0)
- return status;
+ bytes = iomap_zero(inode, pos, length, iomap, srcmap);
+ if (bytes < 0)
+ return bytes;

pos += bytes;
- count -= bytes;
+ length -= bytes;
written += bytes;
if (did_zero)
*did_zero = true;
- } while (count > 0);
+ } while (length > 0);

return written;
}
diff --git a/include/linux/dax.h b/include/linux/dax.h
index 6904d4e0b2e0..951a851a0481 100644
--- a/include/linux/dax.h
+++ b/include/linux/dax.h
@@ -214,8 +214,7 @@ vm_fault_t dax_finish_sync_fault(struct vm_fault *vmf,
int dax_delete_mapping_entry(struct address_space *mapping, pgoff_t index);
int dax_invalidate_mapping_entry_sync(struct address_space *mapping,
pgoff_t index);
-int dax_iomap_zero(loff_t pos, unsigned offset, unsigned size,
- struct iomap *iomap);
+s64 dax_iomap_zero(loff_t pos, u64 length, struct iomap *iomap);
static inline bool dax_mapping(struct address_space *mapping)
{
return mapping->host && IS_DAX(mapping->host);
--
2.28.0
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