ocfs2: Teach ocfs2_get_block() about holes

ocfs2_get_block() didn't understand sparse files, fix that. Also remove some
code that isn't really useful anymore. We can fix up
ocfs2_direct_IO_get_blocks() at the same time.

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

1 files changed, 61 insertions, 38 deletions

diff --git a/fs/ocfs2/aops.c b/fs/ocfs2/aops.c
index 8368036f434a..acf8f0006725 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,
 {
         int err = 0;
         u64 p_blkno, past_eof;
+        struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
 
         mlog_entry("(0x%p, %llu, 0x%p, %d)\n", inode,
                    (unsigned long long)iblock, bh_result, create);
@@ -151,15 +152,6 @@ static int ocfs2_get_block(struct inode *inode, sector_t iblock,
                 goto bail;
         }
 
-        /* this can happen if another node truncs after our extend! */
-        spin_lock(&OCFS2_I(inode)->ip_lock);
-        if (iblock >= ocfs2_clusters_to_blocks(inode->i_sb,
-                                               OCFS2_I(inode)->ip_clusters))
-                err = -EIO;
-        spin_unlock(&OCFS2_I(inode)->ip_lock);
-        if (err)
-                goto bail;
-
         err = ocfs2_extent_map_get_blocks(inode, iblock, &p_blkno, NULL);
         if (err) {
                 mlog(ML_ERROR, "Error %d from get_blocks(0x%p, %llu, 1, "
@@ -168,22 +160,38 @@ static int ocfs2_get_block(struct inode *inode, sector_t iblock,
                 goto bail;
         }
 
-        map_bh(bh_result, inode->i_sb, p_blkno);
-
-        if (bh_result->b_blocknr == 0) {
-                err = -EIO;
-                mlog(ML_ERROR, "iblock = %llu p_blkno = %llu blkno=(%llu)\n",
-                     (unsigned long long)iblock,
-                     (unsigned long long)p_blkno,
-                     (unsigned long long)OCFS2_I(inode)->ip_blkno);
-        }
+        /*
+         * ocfs2 never allocates in this function - the only time we
+         * need to use BH_New is when we're extending i_size on a file
+         * system which doesn't support holes, in which case BH_New
+         * allows block_prepare_write() to zero.
+         */
+        mlog_bug_on_msg(create && p_blkno == 0 && ocfs2_sparse_alloc(osb),
+                        "ino %lu, iblock %llu\n", inode->i_ino,
+                        (unsigned long long)iblock);
+
+        if (p_blkno)
+                map_bh(bh_result, inode->i_sb, p_blkno);
+
+        if (!ocfs2_sparse_alloc(osb)) {
+                if (p_blkno == 0) {
+                        err = -EIO;
+                        mlog(ML_ERROR,
+                             "iblock = %llu p_blkno = %llu blkno=(%llu)\n",
+                             (unsigned long long)iblock,
+                             (unsigned long long)p_blkno,
+                             (unsigned long long)OCFS2_I(inode)->ip_blkno);
+                        mlog(ML_ERROR, "Size %llu, clusters %u\n", (unsigned long long)i_size_read(inode), OCFS2_I(inode)->ip_clusters);
+                        dump_stack();
+                }
 
-        past_eof = ocfs2_blocks_for_bytes(inode->i_sb, i_size_read(inode));
-        mlog(0, "Inode %lu, past_eof = %llu\n", inode->i_ino,
-             (unsigned long long)past_eof);
+                past_eof = ocfs2_blocks_for_bytes(inode->i_sb, i_size_read(inode));
+                mlog(0, "Inode %lu, past_eof = %llu\n", inode->i_ino,
+                     (unsigned long long)past_eof);
 
-        if (create && (iblock >= past_eof))
-                set_buffer_new(bh_result);
+                if (create && (iblock >= past_eof))
+                        set_buffer_new(bh_result);
+        }
 
 bail:
         if (err < 0)
@@ -436,28 +444,15 @@ 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. */
 
-        spin_lock(&OCFS2_I(inode)->ip_lock);
-        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;
-        }
+        inode_blocks = ocfs2_blocks_for_bytes(inode->i_sb, i_size_read(inode));
 
         /*
          * 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;
         }
-        spin_unlock(&OCFS2_I(inode)->ip_lock);
 
         /* This figures out the size of the next contiguous block, and
          * our logical offset */
@@ -470,7 +465,35 @@ static int ocfs2_direct_IO_get_blocks(struct inode *inode, sector_t iblock,
                 goto bail;
         }
 
-        map_bh(bh_result, inode->i_sb, p_blkno);
+        if (!ocfs2_sparse_alloc(OCFS2_SB(inode->i_sb)) && !p_blkno) {
+                ocfs2_error(inode->i_sb,
+                            "Inode %llu has a hole at block %llu\n",
+                            (unsigned long long)OCFS2_I(inode)->ip_blkno,
+                            (unsigned long long)iblock);
+                ret = -EROFS;
+                goto bail;
+        }
+
+        /*
+         * get_more_blocks() expects us to describe a hole by clearing
+         * the mapped bit on bh_result().
+         */
+        if (p_blkno)
+                map_bh(bh_result, inode->i_sb, p_blkno);
+        else {
+                /*
+                 * ocfs2_prepare_inode_for_write() should have caught
+                 * the case where we'd be filling a hole and triggered
+                 * a buffered write instead.
+                 */
+                if (create) {
+                        ret = -EIO;
+                        mlog_errno(ret);
+                        goto bail;
+                }
+
+                clear_buffer_mapped(bh_result);
+        }
 
         /* make sure we don't map more than max_blocks blocks here as
            that's all the kernel will handle at this point. */