iomap: zero newly allocated mapped blocks

File systems like gfs2 don't support delayed allocations or unwritten
extents and thus allocate normal mapped blocks to fill holes.  To
cover the case of such file systems allocating new blocks to fill holes
also zero out mapped blocks with the new flag.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>

diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index e25901ae3ff447712ec6d5635bb7d9ddfd180d3e..181ee8477aad89a82dc731c62f855ce85901a5bd 100644 (file)
--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c
@@ -203,6 +203,14 @@ iomap_read_inline_data(struct inode *inode, struct page *page,
        SetPageUptodate(page);
 }
 
+static inline bool iomap_block_needs_zeroing(struct inode *inode,
+               struct iomap *iomap, loff_t pos)
+{
+       return iomap->type != IOMAP_MAPPED ||
+               (iomap->flags & IOMAP_F_NEW) ||
+               pos >= i_size_read(inode);
+}
+
 static loff_t
 iomap_readpage_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
                struct iomap *iomap)
@@ -226,7 +234,7 @@ iomap_readpage_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
        if (plen == 0)
                goto done;
 
-       if (iomap->type != IOMAP_MAPPED || pos >= i_size_read(inode)) {
+       if (iomap_block_needs_zeroing(inode, iomap, pos)) {
                zero_user(page, poff, plen);
                iomap_set_range_uptodate(page, poff, plen);
                goto done;
@@ -532,7 +540,7 @@ iomap_read_page_sync(struct inode *inode, loff_t block_start, struct page *page,
        struct bio_vec bvec;
        struct bio bio;
 
-       if (iomap->type != IOMAP_MAPPED || block_start >= i_size_read(inode)) {
+       if (iomap_block_needs_zeroing(inode, iomap, block_start)) {
                zero_user_segments(page, poff, from, to, poff + plen);
                iomap_set_range_uptodate(page, poff, plen);
                return 0;