ocfs2: Read from an unwritten extent returns zeros

Return an optional extent flags field from our lookup functions and wire up
callers to treat unwritten regions as holes for the purpose of returning
zeros to the user.

Signed-off-by: Mark Fasheh <mark.fasheh@oracle.com>

1 files changed, 14 insertions, 7 deletions

diff --git a/fs/ocfs2/aops.c b/fs/ocfs2/aops.c
index 014f4f5..eb67c90 100644
--- a/fs/ocfs2/aops.c
+++ b/fs/ocfs2/aops.c
@@ -137,6 +137,7 @@ static int ocfs2_get_block(struct inode *inode, sector_t iblock,
 			   struct buffer_head *bh_result, int create)
 {
 	int err = 0;
+	unsigned int ext_flags;
 	u64 p_blkno, past_eof;
 	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
 
@@ -153,7 +154,8 @@ static int ocfs2_get_block(struct inode *inode, sector_t iblock,
 		goto bail;
 	}
 
-	err = ocfs2_extent_map_get_blocks(inode, iblock, &p_blkno, NULL);
+	err = ocfs2_extent_map_get_blocks(inode, iblock, &p_blkno, NULL,
+					  &ext_flags);
 	if (err) {
 		mlog(ML_ERROR, "Error %d from get_blocks(0x%p, %llu, 1, "
 		     "%llu, NULL)\n", err, inode, (unsigned long long)iblock,
@@ -171,7 +173,8 @@ static int ocfs2_get_block(struct inode *inode, sector_t iblock,
 			"ino %lu, iblock %llu\n", inode->i_ino,
 			(unsigned long long)iblock);
 
-	if (p_blkno)
+	/* Treat the unwritten extent as a hole for zeroing purposes. */
+	if (p_blkno && !(ext_flags & OCFS2_EXT_UNWRITTEN))
 		map_bh(bh_result, inode->i_sb, p_blkno);
 
 	if (!ocfs2_sparse_alloc(osb)) {
@@ -396,7 +399,7 @@ static sector_t ocfs2_bmap(struct address_space *mapping, sector_t block)
 		down_read(&OCFS2_I(inode)->ip_alloc_sem);
 	}
 
-	err = ocfs2_extent_map_get_blocks(inode, block, &p_blkno, NULL);
+	err = ocfs2_extent_map_get_blocks(inode, block, &p_blkno, NULL, NULL);
 
 	if (!INODE_JOURNAL(inode)) {
 		up_read(&OCFS2_I(inode)->ip_alloc_sem);
@@ -438,6 +441,7 @@ static int ocfs2_direct_IO_get_blocks(struct inode *inode, sector_t iblock,
 	int ret;
 	u64 p_blkno, inode_blocks;
 	int contig_blocks;
+	unsigned int ext_flags;
 	unsigned char blocksize_bits = inode->i_sb->s_blocksize_bits;
 	unsigned long max_blocks = bh_result->b_size >> inode->i_blkbits;
 
@@ -458,7 +462,7 @@ static int ocfs2_direct_IO_get_blocks(struct inode *inode, sector_t iblock,
 	/* This figures out the size of the next contiguous block, and
 	 * our logical offset */
 	ret = ocfs2_extent_map_get_blocks(inode, iblock, &p_blkno,
-					  &contig_blocks);
+					  &contig_blocks, &ext_flags);
 	if (ret) {
 		mlog(ML_ERROR, "get_blocks() failed iblock=%llu\n",
 		     (unsigned long long)iblock);
@@ -478,8 +482,10 @@ static int ocfs2_direct_IO_get_blocks(struct inode *inode, sector_t iblock,
 	/*
 	 * get_more_blocks() expects us to describe a hole by clearing
 	 * the mapped bit on bh_result().
+	 *
+	 * Consider an unwritten extent as a hole.
 	 */
-	if (p_blkno)
+	if (p_blkno && !(ext_flags & OCFS2_EXT_UNWRITTEN))
 		map_bh(bh_result, inode->i_sb, p_blkno);
 	else {
 		/*
@@ -1111,7 +1117,8 @@ static ssize_t ocfs2_write(struct file *file, u32 phys, handle_t *handle,
 		}
 	}
 
-	ret = ocfs2_extent_map_get_blocks(inode, v_blkno, &p_blkno, NULL);
+	ret = ocfs2_extent_map_get_blocks(inode, v_blkno, &p_blkno, NULL,
+					  NULL);
 	if (ret < 0) {
 
 		/*
@@ -1215,7 +1222,7 @@ ssize_t ocfs2_buffered_write_cluster(struct file *file, loff_t pos,
 	 */
 	down_write(&OCFS2_I(inode)->ip_alloc_sem);
 
-	ret = ocfs2_get_clusters(inode, wc.w_cpos, &phys, NULL);
+	ret = ocfs2_get_clusters(inode, wc.w_cpos, &phys, NULL, NULL);
 	if (ret) {
 		mlog_errno(ret);
 		goto out_meta;