ocfs2: temporarily remove extent map caching

The code in extent_map.c is not prepared to deal with a subtree being
rotated between lookups. This can happen when filling holes in sparse files.
Instead of a lengthy patch to update the code (which would likely lose the
benefit of caching subtree roots), we remove most of the algorithms and
implement a simple path based lookup. A less ambitious extent caching scheme
will be added in a later patch.
Signed-off-by: Mark Fasheh <mark.fasheh@oracle.com>

fs/ocfs2/alloc.c

@@ -1146,9 +1146,8 @@ static void find_leaf_ins(void *data, struct buffer_head *bh)
  *
  * This function doesn't handle non btree extent lists.
  */
-static int ocfs2_find_leaf(struct inode *inode,
-			   struct ocfs2_extent_list *root_el, u32 cpos,
-			   struct buffer_head **leaf_bh)
+int ocfs2_find_leaf(struct inode *inode, struct ocfs2_extent_list *root_el,
+		    u32 cpos, struct buffer_head **leaf_bh)
 {
 	int ret;
 	struct buffer_head *bh = NULL;

fs/ocfs2/alloc.h

@@ -80,4 +80,7 @@ int ocfs2_commit_truncate(struct ocfs2_super *osb,
 			  struct buffer_head *fe_bh,
 			  struct ocfs2_truncate_context *tc);
 
+int ocfs2_find_leaf(struct inode *inode, struct ocfs2_extent_list *root_el,
+		    u32 cpos, struct buffer_head **leaf_bh);
+
 #endif /* OCFS2_ALLOC_H */

fs/ocfs2/aops.c

@@ -158,8 +158,7 @@ static int ocfs2_get_block(struct inode *inode, sector_t iblock,
 	if (err)
 		goto bail;
 
-	err = ocfs2_extent_map_get_blocks(inode, iblock, 1, &p_blkno,
-					  NULL);
+	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, "
 		     "%llu, NULL)\n", err, inode, (unsigned long long)iblock,
@@ -499,8 +498,7 @@ 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, 1, &p_blkno,
-					  NULL);
+	err = ocfs2_extent_map_get_blocks(inode, block, &p_blkno, NULL);
 
 	if (!INODE_JOURNAL(inode)) {
 		up_read(&OCFS2_I(inode)->ip_alloc_sem);
@@ -574,7 +572,7 @@ 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, 1, &p_blkno,
+	ret = ocfs2_extent_map_get_blocks(inode, iblock, &p_blkno,
 					  &contig_blocks);
 	if (ret) {
 		mlog(ML_ERROR, "get_blocks() failed iblock=%llu\n",

fs/ocfs2/dir.c

@@ -379,7 +379,7 @@ int ocfs2_do_extend_dir(struct super_block *sb,
 
 	status = ocfs2_extent_map_get_blocks(dir, (dir->i_blocks >>
 						   (sb->s_blocksize_bits - 9)),
-					     1, &p_blkno, NULL);
+					     &p_blkno, NULL);
 	if (status < 0) {
 		mlog_errno(status);
 		goto bail;

fs/ocfs2/dlmglue.c

@@ -1614,10 +1614,6 @@ static int ocfs2_meta_lock_update(struct inode *inode,
 	 * for the inode metadata. */
 	ocfs2_metadata_cache_purge(inode);
 
-	/* will do nothing for inode types that don't use the extent
-	 * map (bitmap files, etc) */
-	ocfs2_extent_map_trunc(inode, 0);
-
 	if (ocfs2_meta_lvb_is_trustable(inode, lockres)) {
 		mlog(0, "Trusting LVB on inode %llu\n",
 		     (unsigned long long)oi->ip_blkno);

fs/ocfs2/extent_map.h

@@ -25,22 +25,7 @@
 #ifndef _EXTENT_MAP_H
 #define _EXTENT_MAP_H
 
-int init_ocfs2_extent_maps(void);
-void exit_ocfs2_extent_maps(void);
-
-/*
- * EVERY CALL here except _init, _trunc, and _drop expects alloc_sem
- * to be held.  The allocation cannot change at all while the map is
- * in the process of being updated.
- */
-int ocfs2_extent_map_init(struct inode *inode);
-int ocfs2_extent_map_append(struct inode *inode,
-			    struct ocfs2_extent_rec *rec,
-			    u32 new_clusters);
-int ocfs2_extent_map_get_blocks(struct inode *inode,
-				u64 v_blkno, int count,
-				u64 *p_blkno, int *ret_count);
-int ocfs2_extent_map_drop(struct inode *inode, u32 new_clusters);
-int ocfs2_extent_map_trunc(struct inode *inode, u32 new_clusters);
+int ocfs2_extent_map_get_blocks(struct inode *inode, u64 v_blkno, u64 *p_blkno,
+				int *ret_count);
 
 #endif  /* _EXTENT_MAP_H */

fs/ocfs2/inode.c

@@ -1003,9 +1003,6 @@ void ocfs2_clear_inode(struct inode *inode)
 			"Clear inode of %llu, inode has io markers\n",
 			(unsigned long long)oi->ip_blkno);
 
-	ocfs2_extent_map_drop(inode, 0);
-	ocfs2_extent_map_init(inode);
-
 	status = ocfs2_drop_inode_locks(inode);
 	if (status < 0)
 		mlog_errno(status);
@@ -1102,8 +1099,7 @@ struct buffer_head *ocfs2_bread(struct inode *inode,
 		return NULL;
 	}
 
-	tmperr = ocfs2_extent_map_get_blocks(inode, block, 1,
-					     &p_blkno, NULL);
+	tmperr = ocfs2_extent_map_get_blocks(inode, block, &p_blkno, NULL);
 	if (tmperr < 0) {
 		mlog_errno(tmperr);
 		goto fail;

fs/ocfs2/inode.h

@@ -43,7 +43,6 @@ struct ocfs2_inode_info
 	spinlock_t			ip_lock;
 	u32				ip_open_count;
 	u32				ip_clusters;
-	struct ocfs2_extent_map		ip_map;
 	struct list_head		ip_io_markers;
 
 	struct mutex			ip_io_mutex;

fs/ocfs2/journal.c

@@ -670,8 +670,7 @@ static int ocfs2_force_read_journal(struct inode *inode)
 	       (inode->i_blocks >> (inode->i_sb->s_blocksize_bits - 9))) {
 
 		status = ocfs2_extent_map_get_blocks(inode, v_blkno,
-						     1, &p_blkno,
-						     &p_blocks);
+						     &p_blkno, &p_blocks);
 		if (status < 0) {
 			mlog_errno(status);
 			goto bail;

fs/ocfs2/namei.c

@@ -1511,8 +1511,7 @@ static int ocfs2_create_symlink_data(struct ocfs2_super *osb,
 		goto bail;
 	}
 
-	status = ocfs2_extent_map_get_blocks(inode, 0, 1, &p_blkno,
-					     &p_blocks);
+	status = ocfs2_extent_map_get_blocks(inode, 0, &p_blkno, &p_blocks);
 	if (status < 0) {
 		mlog_errno(status);
 		goto bail;

fs/ocfs2/ocfs2.h

@@ -46,11 +46,6 @@
 #include "endian.h"
 #include "ocfs2_lockid.h"
 
-struct ocfs2_extent_map {
-	u32		em_clusters;
-	struct rb_root	em_extents;
-};
-
 /* Most user visible OCFS2 inodes will have very few pieces of
  * metadata, but larger files (including bitmaps, etc) must be taken
  * into account when designing an access scheme. We allow a small

fs/ocfs2/slot_map.c

@@ -197,7 +197,7 @@ int ocfs2_init_slot_info(struct ocfs2_super *osb)
 		goto bail;
 	}
 
-	status = ocfs2_extent_map_get_blocks(inode, 0ULL, 1, &blkno, NULL);
+	status = ocfs2_extent_map_get_blocks(inode, 0ULL, &blkno, NULL);
 	if (status < 0) {
 		mlog_errno(status);
 		goto bail;

fs/ocfs2/super.c

@@ -806,9 +806,6 @@ static int __init ocfs2_init(void)
 
 	ocfs2_print_version();
 
-	if (init_ocfs2_extent_maps())
-		return -ENOMEM;
-
 	status = init_ocfs2_uptodate_cache();
 	if (status < 0) {
 		mlog_errno(status);
@@ -837,7 +834,6 @@ static int __init ocfs2_init(void)
 	if (status < 0) {
 		ocfs2_free_mem_caches();
 		exit_ocfs2_uptodate_cache();
-		exit_ocfs2_extent_maps();
 	}
 
 	mlog_exit(status);
@@ -863,8 +859,6 @@ static void __exit ocfs2_exit(void)
 
 	unregister_filesystem(&ocfs2_fs_type);
 
-	exit_ocfs2_extent_maps();
-
 	exit_ocfs2_uptodate_cache();
 
 	mlog_exit_void();
@@ -948,7 +942,6 @@ static void ocfs2_inode_init_once(void *data,
 		oi->ip_flags = 0;
 		oi->ip_open_count = 0;
 		spin_lock_init(&oi->ip_lock);
-		ocfs2_extent_map_init(&oi->vfs_inode);
 		INIT_LIST_HEAD(&oi->ip_io_markers);
 		oi->ip_created_trans = 0;
 		oi->ip_last_trans = 0;