iomap: Support inline data with block size < page size

Remove the restriction that inline data must start on a page boundary
in a file.  This allows, for example, the first 2KiB to be stored out
of line and the trailing 30 bytes to be stored inline.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>

diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index 1d31ff6..28cfa7f 100644 (file)
--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c
@@ -209,28 +209,26 @@ static int iomap_read_inline_data(struct inode *inode, struct page *page,
                struct iomap *iomap)
 {
        size_t size = i_size_read(inode) - iomap->offset;
+       size_t poff = offset_in_page(iomap->offset);
        void *addr;
 
        if (PageUptodate(page))
-               return 0;
+               return PAGE_SIZE - poff;
 
-       /* inline data must start page aligned in the file */
-       if (WARN_ON_ONCE(offset_in_page(iomap->offset)))
-               return -EIO;
        if (WARN_ON_ONCE(size > PAGE_SIZE -
                         offset_in_page(iomap->inline_data)))
                return -EIO;
        if (WARN_ON_ONCE(size > iomap->length))
                return -EIO;
-       if (WARN_ON_ONCE(page_has_private(page)))
-               return -EIO;
+       if (poff > 0)
+               iomap_page_create(inode, page);
 
-       addr = kmap_atomic(page);
+       addr = kmap_atomic(page) + poff;
        memcpy(addr, iomap->inline_data, size);
-       memset(addr + size, 0, PAGE_SIZE - size);
+       memset(addr + size, 0, PAGE_SIZE - poff - size);
        kunmap_atomic(addr);
-       SetPageUptodate(page);
-       return 0;
+       iomap_set_range_uptodate(page, poff, PAGE_SIZE - poff);
+       return PAGE_SIZE - poff;
 }
 
 static inline bool iomap_block_needs_zeroing(struct inode *inode,
@@ -252,13 +250,8 @@ iomap_readpage_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
        unsigned poff, plen;
        sector_t sector;
 
-       if (iomap->type == IOMAP_INLINE) {
-               int ret = iomap_read_inline_data(inode, page, iomap);
-
-               if (ret)
-                       return ret;
-               return PAGE_SIZE;
-       }
+       if (iomap->type == IOMAP_INLINE)
+               return iomap_read_inline_data(inode, page, iomap);
 
        /* zero post-eof blocks as the page may be mapped */
        iop = iomap_page_create(inode, page);
@@ -593,10 +586,15 @@ __iomap_write_begin(struct inode *inode, loff_t pos, unsigned len, int flags,
 static int iomap_write_begin_inline(struct inode *inode,
                struct page *page, struct iomap *srcmap)
 {
+       int ret;
+
        /* needs more work for the tailpacking case; disable for now */
        if (WARN_ON_ONCE(srcmap->offset != 0))
                return -EIO;
-       return iomap_read_inline_data(inode, page, srcmap);
+       ret = iomap_read_inline_data(inode, page, srcmap);
+       if (ret < 0)
+               return ret;
+       return 0;
 }
 
 static int