ocfs2: Allow direct I/O read past end of file

ocfs2_direct_IO_get_blocks() was incorrectly returning -EIO for a direct I/O
read whose start block was past the end of the file allocation tree. Fix
things so that we return a hole instead. do_direct_IO() will then notice
that the range start is past eof and return a short read.

While there, remove the unused vbo_max variable.

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

1 files changed, 17 insertions, 7 deletions

diff --git a/fs/ocfs2/aops.c b/fs/ocfs2/aops.c
index ef6cd30108a9..93628b02ef5d 100644
--- a/fs/ocfs2/aops.c
+++ b/fs/ocfs2/aops.c
@@ -540,8 +540,7 @@ static int ocfs2_direct_IO_get_blocks(struct inode *inode, sector_t iblock,
                                      struct buffer_head *bh_result, int create)
 {
         int ret;
-        u64 vbo_max; /* file offset, max_blocks from iblock */
-        u64 p_blkno;
+        u64 p_blkno, inode_blocks;
         int contig_blocks;
         unsigned char blocksize_bits = inode->i_sb->s_blocksize_bits;
         unsigned long max_blocks = bh_result->b_size >> inode->i_blkbits;
@@ -550,12 +549,23 @@ static int ocfs2_direct_IO_get_blocks(struct inode *inode, sector_t iblock,
          * nicely aligned and of the right size, so there's no need
          * for us to check any of that. */
 
-        vbo_max = ((u64)iblock + max_blocks) << blocksize_bits;
-
         spin_lock(&OCFS2_I(inode)->ip_lock);
-        if ((iblock + max_blocks) >
-            ocfs2_clusters_to_blocks(inode->i_sb,
-                                     OCFS2_I(inode)->ip_clusters)) {
+        inode_blocks = ocfs2_clusters_to_blocks(inode->i_sb,
+                                                OCFS2_I(inode)->ip_clusters);
+
+        /*
+         * For a read which begins past the end of file, we return a hole.
+         */
+        if (!create && (iblock >= inode_blocks)) {
+                spin_unlock(&OCFS2_I(inode)->ip_lock);
+                ret = 0;
+                goto bail;
+        }
+
+        /*
+         * Any write past EOF is not allowed because we'd be extending.
+         */
+        if (create && (iblock + max_blocks) > inode_blocks) {
                 spin_unlock(&OCFS2_I(inode)->ip_lock);
                 ret = -EIO;
                 goto bail;