[PATCH 01/15] iomap: Use a srcmap for a read-modify-write I/O

Goldwyn Rodrigues
2019-09-05T15:07:00Z

A preparation patch for copy-on-write (CoW).
The srcmap is used to identify where the read is to be performed
from. This is passed to iomap->begin() of the respective
filesystem, which is supposed to put in the details for
reading before performing the copy for CoW.

Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
---
fs/dax.c | 8 +++++---
fs/ext2/inode.c | 2 +-
fs/ext4/inode.c | 2 +-
fs/gfs2/bmap.c | 3 ++-
fs/iomap/apply.c | 5 +++--
fs/iomap/buffered-io.c | 14 +++++++-------
fs/iomap/direct-io.c | 2 +-
fs/iomap/fiemap.c | 4 ++--
fs/iomap/seek.c | 4 ++--
fs/iomap/swapfile.c | 3 ++-
fs/xfs/xfs_iomap.c | 9 ++++++---
include/linux/iomap.h | 5 +++--
12 files changed, 35 insertions(+), 26 deletions(-)

diff --git a/fs/dax.c b/fs/dax.c
index 6bf81f931de3..e961d8dc23ef 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;
@@ -1248,6 +1248,7 @@ static vm_fault_t dax_iomap_pte_fault(struct vm_fault *vmf, pfn_t *pfnp,
unsigned long vaddr = vmf->address;
loff_t pos = (loff_t)vmf->pgoff << PAGE_SHIFT;
struct iomap iomap = { 0 };
+ struct iomap srcmap = { 0 };
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) {
@@ -1472,6 +1473,7 @@ static vm_fault_t dax_iomap_pmd_fault(struct vm_fault *vmf, pfn_t *pfnp,
struct inode *inode = mapping->host;
vm_fault_t result = VM_FAULT_FALLBACK;
struct iomap iomap = { 0 };
+ struct iomap srcmap = { 0 };
pgoff_t max_pgoff;
void *entry;
loff_t pos;
@@ -1546,7 +1548,7 @@ 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;

diff --git a/fs/ext2/inode.c b/fs/ext2/inode.c
index 7004ce581a32..467c13ff6b40 100644
--- a/fs/ext2/inode.c
+++ b/fs/ext2/inode.c
@@ -801,7 +801,7 @@ int ext2_get_block(struct inode *inode, sector_t iblock,

#ifdef CONFIG_FS_DAX
static int ext2_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
- unsigned flags, struct iomap *iomap)
+ unsigned flags, struct iomap *iomap, struct iomap *srcmap)
{
unsigned int blkbits = inode->i_blkbits;
unsigned long first_block = offset >> blkbits;
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 420fe3deed39..918f94eff799 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -3453,7 +3453,7 @@ static bool ext4_inode_datasync_dirty(struct inode *inode)
}

static int ext4_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
- unsigned flags, struct iomap *iomap)
+ unsigned flags, struct iomap *iomap, struct iomap *srcmap)
{
struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
unsigned int blkbits = inode->i_blkbits;
diff --git a/fs/gfs2/bmap.c b/fs/gfs2/bmap.c
index 4f8b5fd6c81f..0189262989f2 100644
--- a/fs/gfs2/bmap.c
+++ b/fs/gfs2/bmap.c
@@ -1164,7 +1164,8 @@ static int gfs2_iomap_begin_write(struct inode *inode, loff_t pos,
}

static int gfs2_iomap_begin(struct inode *inode, loff_t pos, loff_t length,
- unsigned flags, struct iomap *iomap)
+ unsigned flags, struct iomap *iomap,
+ struct iomap *srcmap)
{
struct gfs2_inode *ip = GFS2_I(inode);
struct metapath mp = { .mp_aheight = 1, };
diff --git a/fs/iomap/apply.c b/fs/iomap/apply.c
index 54c02aecf3cd..6cdb362fff36 100644
--- a/fs/iomap/apply.c
+++ b/fs/iomap/apply.c
@@ -24,6 +24,7 @@ iomap_apply(struct inode *inode, loff_t pos, loff_t length, unsigned flags,
const struct iomap_ops *ops, void *data, iomap_actor_t actor)
{
struct iomap iomap = { 0 };
+ struct iomap srcmap = { 0 };
loff_t written = 0, ret;

/*
@@ -38,7 +39,7 @@ iomap_apply(struct inode *inode, loff_t pos, loff_t length, unsigned flags,
* expose transient stale data. If the reserve fails, we can safely
* back out at this point as there is nothing to undo.
*/
- ret = ops->iomap_begin(inode, pos, length, flags, &iomap);
+ ret = ops->iomap_begin(inode, pos, length, flags, &iomap, &srcmap);
if (ret)
return ret;
if (WARN_ON(iomap.offset > pos))
@@ -58,7 +59,7 @@ iomap_apply(struct inode *inode, loff_t pos, loff_t length, unsigned flags,
* we can do the copy-in page by page without having to worry about
* failures exposing transient data.
*/
- written = actor(inode, pos, length, data, &iomap);
+ written = actor(inode, pos, length, data, &iomap, &srcmap);

/*
* Now the data has been copied, commit the range we've copied. This
diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index e25901ae3ff4..f27756c0b31c 100644
--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c
@@ -205,7 +205,7 @@ iomap_read_inline_data(struct inode *inode, struct page *page,

static loff_t
iomap_readpage_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
- struct iomap *iomap)
+ struct iomap *iomap, struct iomap *srcmap)
{
struct iomap_readpage_ctx *ctx = data;
struct page *page = ctx->cur_page;
@@ -351,7 +351,7 @@ iomap_next_page(struct inode *inode, struct list_head *pages, loff_t pos,

static loff_t
iomap_readpages_actor(struct inode *inode, loff_t pos, loff_t length,
- void *data, struct iomap *iomap)
+ void *data, struct iomap *iomap, struct iomap *srcmap)
{
struct iomap_readpage_ctx *ctx = data;
loff_t done, ret;
@@ -371,7 +371,7 @@ iomap_readpages_actor(struct inode *inode, loff_t pos, loff_t length,
ctx->cur_page_in_bio = false;
}
ret = iomap_readpage_actor(inode, pos + done, length - done,
- ctx, iomap);
+ ctx, iomap, srcmap);
}

return done;
@@ -736,7 +736,7 @@ iomap_write_end(struct inode *inode, loff_t pos, unsigned len,

static loff_t
iomap_write_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
- struct iomap *iomap)
+ struct iomap *iomap, struct iomap *srcmap)
{
struct iov_iter *i = data;
long status = 0;
@@ -853,7 +853,7 @@ __iomap_read_page(struct inode *inode, loff_t offset)

static loff_t
iomap_dirty_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
- struct iomap *iomap)
+ struct iomap *iomap, struct iomap *srcmap)
{
long status = 0;
ssize_t written = 0;
@@ -942,7 +942,7 @@ static int iomap_dax_zero(loff_t pos, unsigned offset, unsigned bytes,

static loff_t
iomap_zero_range_actor(struct inode *inode, loff_t pos, loff_t count,
- void *data, struct iomap *iomap)
+ void *data, struct iomap *iomap, struct iomap *srcmap)
{
bool *did_zero = data;
loff_t written = 0;
@@ -1011,7 +1011,7 @@ EXPORT_SYMBOL_GPL(iomap_truncate_page);

static loff_t
iomap_page_mkwrite_actor(struct inode *inode, loff_t pos, loff_t length,
- void *data, struct iomap *iomap)
+ void *data, struct iomap *iomap, struct iomap *srcmap)
{
struct page *page = data;
int ret;
diff --git a/fs/iomap/direct-io.c b/fs/iomap/direct-io.c
index 1fc28c2da279..e3ccbf7daaae 100644
--- a/fs/iomap/direct-io.c
+++ b/fs/iomap/direct-io.c
@@ -358,7 +358,7 @@ iomap_dio_inline_actor(struct inode *inode, loff_t pos, loff_t length,

static loff_t
iomap_dio_actor(struct inode *inode, loff_t pos, loff_t length,
- void *data, struct iomap *iomap)
+ void *data, struct iomap *iomap, struct iomap *srcmap)
{
struct iomap_dio *dio = data;

diff --git a/fs/iomap/fiemap.c b/fs/iomap/fiemap.c
index f26fdd36e383..690ef2d7c6c8 100644
--- a/fs/iomap/fiemap.c
+++ b/fs/iomap/fiemap.c
@@ -44,7 +44,7 @@ static int iomap_to_fiemap(struct fiemap_extent_info *fi,

static loff_t
iomap_fiemap_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
- struct iomap *iomap)
+ struct iomap *iomap, struct iomap *srcmap)
{
struct fiemap_ctx *ctx = data;
loff_t ret = length;
@@ -111,7 +111,7 @@ EXPORT_SYMBOL_GPL(iomap_fiemap);

static loff_t
iomap_bmap_actor(struct inode *inode, loff_t pos, loff_t length,
- void *data, struct iomap *iomap)
+ void *data, struct iomap *iomap, struct iomap *srcmap)
{
sector_t *bno = data, addr;

diff --git a/fs/iomap/seek.c b/fs/iomap/seek.c
index c04bad4b2b43..89f61d93c0bc 100644
--- a/fs/iomap/seek.c
+++ b/fs/iomap/seek.c
@@ -119,7 +119,7 @@ page_cache_seek_hole_data(struct inode *inode, loff_t offset, loff_t length,

static loff_t
iomap_seek_hole_actor(struct inode *inode, loff_t offset, loff_t length,
- void *data, struct iomap *iomap)
+ void *data, struct iomap *iomap, struct iomap *srcmap)
{
switch (iomap->type) {
case IOMAP_UNWRITTEN:
@@ -165,7 +165,7 @@ EXPORT_SYMBOL_GPL(iomap_seek_hole);

static loff_t
iomap_seek_data_actor(struct inode *inode, loff_t offset, loff_t length,
- void *data, struct iomap *iomap)
+ void *data, struct iomap *iomap, struct iomap *srcmap)
{
switch (iomap->type) {
case IOMAP_HOLE:
diff --git a/fs/iomap/swapfile.c b/fs/iomap/swapfile.c
index 152a230f668d..a648dbf6991e 100644
--- a/fs/iomap/swapfile.c
+++ b/fs/iomap/swapfile.c
@@ -76,7 +76,8 @@ static int iomap_swapfile_add_extent(struct iomap_swapfile_info *isi)
* distinction between written and unwritten extents.
*/
static loff_t iomap_swapfile_activate_actor(struct inode *inode, loff_t pos,
- loff_t count, void *data, struct iomap *iomap)
+ loff_t count, void *data, struct iomap *iomap,
+ struct iomap *srcmap)
{
struct iomap_swapfile_info *isi = data;
int error;
diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c
index 3a4310d7cb59..8321733c16c3 100644
--- a/fs/xfs/xfs_iomap.c
+++ b/fs/xfs/xfs_iomap.c
@@ -922,7 +922,8 @@ xfs_file_iomap_begin(
loff_t offset,
loff_t length,
unsigned flags,
- struct iomap *iomap)
+ struct iomap *iomap,
+ struct iomap *srcmap)
{
struct xfs_inode *ip = XFS_I(inode);
struct xfs_mount *mp = ip->i_mount;
@@ -1145,7 +1146,8 @@ xfs_seek_iomap_begin(
loff_t offset,
loff_t length,
unsigned flags,
- struct iomap *iomap)
+ struct iomap *iomap,
+ struct iomap *srcmap)
{
struct xfs_inode *ip = XFS_I(inode);
struct xfs_mount *mp = ip->i_mount;
@@ -1231,7 +1233,8 @@ xfs_xattr_iomap_begin(
loff_t offset,
loff_t length,
unsigned flags,
- struct iomap *iomap)
+ struct iomap *iomap,
+ struct iomap *srcmap)
{
struct xfs_inode *ip = XFS_I(inode);
struct xfs_mount *mp = ip->i_mount;
diff --git a/include/linux/iomap.h b/include/linux/iomap.h
index 7aa5d6117936..9782a79dde59 100644
--- a/include/linux/iomap.h
+++ b/include/linux/iomap.h
@@ -110,7 +110,8 @@ struct iomap_ops {
* The actual length is returned in iomap->length.
*/
int (*iomap_begin)(struct inode *inode, loff_t pos, loff_t length,
- unsigned flags, struct iomap *iomap);
+ unsigned flags, struct iomap *iomap,
+ struct iomap *srcmap);

/*
* Commit and/or unreserve space previous allocated using iomap_begin.
@@ -126,7 +127,7 @@ struct iomap_ops {
* Main iomap iterator function.
*/
typedef loff_t (*iomap_actor_t)(struct inode *inode, loff_t pos, loff_t len,
- void *data, struct iomap *iomap);
+ void *data, struct iomap *iomap, struct iomap *srcmap);

loff_t iomap_apply(struct inode *inode, loff_t pos, loff_t length,
unsigned flags, const struct iomap_ops *ops, void *data,
--
2.16.4