iomap: generic inline data handling

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>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>

diff --git a/fs/iomap.c b/fs/iomap.c
index 9c45445..4aecd7c 100644 (file)
--- 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 @@ again:
 
                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 a044a82..10d6cff 100644 (file)
--- a/include/linux/iomap.h
+++ b/include/linux/iomap.h
@@ -55,6 +55,7 @@ struct iomap {
        u16                     flags;  /* flags for mapping */
        struct block_device     *bdev;  /* block device for I/O */
        struct dax_device       *dax_dev; /* dax_dev for dax operations */
+       void                    *inline_data;
 };
 
 /*