[PATCH 5/6] iomap: generic inline data handling

Christoph Hellwig
2018-06-14T12:04:56Z

From: Andreas Gruenbacher <agruenba@redhat.com>

Add generic inline data handling by adding a pointer to the inline data
region to struct iomap. When handling a buffered IOMAP_INLINE write,
iomap_write_begin will copy the current inline data from the inline data
region into the page cache, and iomap_write_end will copy the changes in
the page cache back to the inline data region.

This doesn't cover inline data reads and direct I/O yet because so far,
we have no users.

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
[hch: small cleanups to better fit in with other iomap work]
Signed-off-by: Christoph Hellwig <hch@lst.de>
---
fs/iomap.c | 62 ++++++++++++++++++++++++++++++++++++++-----
include/linux/iomap.h | 1 +
2 files changed, 56 insertions(+), 7 deletions(-)

diff --git a/fs/iomap.c b/fs/iomap.c
index bf1e81b08962..6d5a2ebe5dd8 100644
--- a/fs/iomap.c
+++ b/fs/iomap.c
@@ -103,6 +103,26 @@ iomap_sector(struct iomap *iomap, loff_t pos)
return (iomap->addr + pos - iomap->offset) >> SECTOR_SHIFT;
}

+static void
+iomap_read_inline_data(struct inode *inode, struct page *page,
+ struct iomap *iomap)
+{
+ size_t size = i_size_read(inode);
+ void *addr;
+
+ if (PageUptodate(page))
+ return;
+
+ BUG_ON(page->index);
+ BUG_ON(size > PAGE_SIZE - offset_in_page(iomap->inline_data));
+
+ addr = kmap_atomic(page);
+ memcpy(addr, iomap->inline_data, size);
+ memset(addr + size, 0, PAGE_SIZE - size);
+ kunmap_atomic(addr);
+ SetPageUptodate(page);
+}
+
static void
iomap_write_failed(struct inode *inode, loff_t pos, unsigned len)
{
@@ -133,7 +153,11 @@ iomap_write_begin(struct inode *inode, loff_t pos, unsigned len, unsigned flags,
if (!page)
return -ENOMEM;

- status = __block_write_begin_int(page, pos, len, NULL, iomap);
+ if (iomap->type == IOMAP_INLINE)
+ iomap_read_inline_data(inode, page, iomap);
+ else
+ status = __block_write_begin_int(page, pos, len, NULL, iomap);
+
if (unlikely(status)) {
unlock_page(page);
put_page(page);
@@ -146,14 +170,37 @@ iomap_write_begin(struct inode *inode, loff_t pos, unsigned len, unsigned flags,
return status;
}

+static int
+iomap_write_end_inline(struct inode *inode, struct page *page,
+ struct iomap *iomap, loff_t pos, unsigned copied)
+{
+ void *addr;
+
+ WARN_ON_ONCE(!PageUptodate(page));
+ BUG_ON(pos + copied > PAGE_SIZE - offset_in_page(iomap->inline_data));
+
+ addr = kmap_atomic(page);
+ memcpy(iomap->inline_data + pos, addr + pos, copied);
+ kunmap_atomic(addr);
+
+ mark_inode_dirty(inode);
+ __generic_write_end(inode, pos, copied, page);
+ return copied;
+}
+
static int
iomap_write_end(struct inode *inode, loff_t pos, unsigned len,
- unsigned copied, struct page *page)
+ unsigned copied, struct page *page, struct iomap *iomap)
{
int ret;

- ret = generic_write_end(NULL, inode->i_mapping, pos, len,
- copied, page, NULL);
+ if (iomap->type == IOMAP_INLINE) {
+ ret = iomap_write_end_inline(inode, page, iomap, pos, copied);
+ } else {
+ ret = generic_write_end(NULL, inode->i_mapping, pos, len,
+ copied, page, NULL);
+ }
+
if (ret < len)
iomap_write_failed(inode, pos, len);
return ret;
@@ -208,7 +255,8 @@ iomap_write_actor(struct inode *inode, loff_t pos, loff_t length, void *data,

flush_dcache_page(page);

- status = iomap_write_end(inode, pos, bytes, copied, page);
+ status = iomap_write_end(inode, pos, bytes, copied, page,
+ iomap);
if (unlikely(status < 0))
break;
copied = status;
@@ -302,7 +350,7 @@ iomap_dirty_actor(struct inode *inode, loff_t pos, loff_t length, void *data,

WARN_ON_ONCE(!PageUptodate(page));

- status = iomap_write_end(inode, pos, bytes, bytes, page);
+ status = iomap_write_end(inode, pos, bytes, bytes, page, iomap);
if (unlikely(status <= 0)) {
if (WARN_ON_ONCE(status == 0))
return -EIO;
@@ -354,7 +402,7 @@ static int iomap_zero(struct inode *inode, loff_t pos, unsigned offset,
zero_user(page, offset, bytes);
mark_page_accessed(page);

- return iomap_write_end(inode, pos, bytes, bytes, page);
+ return iomap_write_end(inode, pos, bytes, bytes, page, iomap);
}

static int iomap_dax_zero(loff_t pos, unsigned offset, unsigned bytes,
diff --git a/include/linux/iomap.h b/include/linux/iomap.h
index 212f4d59bcbf..69ef622f650e 100644
--- a/include/linux/iomap.h
+++ b/include/linux/iomap.h
@@ -56,6 +56,7 @@ struct iomap {
union {
struct block_device *bdev;
struct dax_device *dax_dev;
+ void *inline_data;
};
};

--
2.17.1