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authorGoldwyn Rodrigues <rgoldwyn@suse.com>2019-10-18 16:44:10 -0700
committerDarrick J. Wong <darrick.wong@oracle.com>2019-10-21 08:51:59 -0700
commitc039b99792726346ad46ff17c5a5bcb77a5edac4 (patch)
treee9034adc21c6fc3ad6fc775e8f3225e35b015d50 /fs/dax.c
parenteb81cf9d0e18d438e27339e0d1a49d3ac8644674 (diff)
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iomap: use a srcmap for a read-modify-write I/O
The srcmap is used to identify where the read is to be performed from. It is passed to ->iomap_begin, which can fill it in if we need to read data for partially written blocks from a different location than the write target. The srcmap is only supported for buffered writes so far. Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com> [hch: merged two patches, removed the IOMAP_F_COW flag, use iomap as srcmap if not set, adjust length down to srcmap end as well] Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> Acked-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Diffstat (limited to 'fs/dax.c')
-rw-r--r--fs/dax.c13
1 files changed, 8 insertions, 5 deletions
diff --git a/fs/dax.c b/fs/dax.c
index 6bf81f931de3..68eef98cd9c4 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -1090,7 +1090,7 @@ EXPORT_SYMBOL_GPL(__dax_zero_page_range);
static loff_t
dax_iomap_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
- struct iomap *iomap)
+ struct iomap *iomap, struct iomap *srcmap)
{
struct block_device *bdev = iomap->bdev;
struct dax_device *dax_dev = iomap->dax_dev;
@@ -1247,7 +1247,8 @@ static vm_fault_t dax_iomap_pte_fault(struct vm_fault *vmf, pfn_t *pfnp,
struct inode *inode = mapping->host;
unsigned long vaddr = vmf->address;
loff_t pos = (loff_t)vmf->pgoff << PAGE_SHIFT;
- struct iomap iomap = { 0 };
+ struct iomap iomap = { .type = IOMAP_HOLE };
+ struct iomap srcmap = { .type = IOMAP_HOLE };
unsigned flags = IOMAP_FAULT;
int error, major = 0;
bool write = vmf->flags & FAULT_FLAG_WRITE;
@@ -1292,7 +1293,7 @@ static vm_fault_t dax_iomap_pte_fault(struct vm_fault *vmf, pfn_t *pfnp,
* the file system block size to be equal the page size, which means
* that we never have to deal with more than a single extent here.
*/
- error = ops->iomap_begin(inode, pos, PAGE_SIZE, flags, &iomap);
+ error = ops->iomap_begin(inode, pos, PAGE_SIZE, flags, &iomap, &srcmap);
if (iomap_errp)
*iomap_errp = error;
if (error) {
@@ -1471,7 +1472,8 @@ static vm_fault_t dax_iomap_pmd_fault(struct vm_fault *vmf, pfn_t *pfnp,
unsigned int iomap_flags = (write ? IOMAP_WRITE : 0) | IOMAP_FAULT;
struct inode *inode = mapping->host;
vm_fault_t result = VM_FAULT_FALLBACK;
- struct iomap iomap = { 0 };
+ struct iomap iomap = { .type = IOMAP_HOLE };
+ struct iomap srcmap = { .type = IOMAP_HOLE };
pgoff_t max_pgoff;
void *entry;
loff_t pos;
@@ -1546,7 +1548,8 @@ static vm_fault_t dax_iomap_pmd_fault(struct vm_fault *vmf, pfn_t *pfnp,
* to look up our filesystem block.
*/
pos = (loff_t)xas.xa_index << PAGE_SHIFT;
- error = ops->iomap_begin(inode, pos, PMD_SIZE, iomap_flags, &iomap);
+ error = ops->iomap_begin(inode, pos, PMD_SIZE, iomap_flags, &iomap,
+ &srcmap);
if (error)
goto unlock_entry;