ext4: refactor ext4_move_extents code base
ext4_move_extents is too complex for review. It has duplicate almost
each function available in the rest of other codebase. It has useless
artificial restriction orig_offset == donor_offset. But in fact logic
of ext4_move_extents is very simple:
Iterate extents one by one (similar to ext4_fill_fiemap_extents)
->Iterate each page covered extent (similar to generic_perform_write)
->swap extents for covered by page (can be shared with IOC_MOVE_DATA)
Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index 1b76834..73d9ae9 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -291,6 +291,19 @@
return size;
}
+static inline int
+ext4_force_split_extent_at(handle_t *handle, struct inode *inode,
+ struct ext4_ext_path *path, ext4_lblk_t lblk,
+ int nofail)
+{
+ int unwritten = ext4_ext_is_unwritten(path[path->p_depth].p_ext);
+
+ return ext4_split_extent_at(handle, inode, path, lblk, unwritten ?
+ EXT4_EXT_MARK_UNWRIT1|EXT4_EXT_MARK_UNWRIT2 : 0,
+ EXT4_EX_NOCACHE | EXT4_GET_BLOCKS_PRE_IO |
+ (nofail ? EXT4_GET_BLOCKS_METADATA_NOFAIL:0));
+}
+
/*
* Calculate the number of metadata blocks needed
* to allocate @blocks
@@ -1559,7 +1572,7 @@
* allocated block. Thus, index entries have to be consistent
* with leaves.
*/
-static ext4_lblk_t
+ext4_lblk_t
ext4_ext_next_allocated_block(struct ext4_ext_path *path)
{
int depth;
@@ -2854,24 +2867,14 @@
*/
if (end >= ee_block &&
end < ee_block + ext4_ext_get_actual_len(ex) - 1) {
- int split_flag = 0;
-
- if (ext4_ext_is_unwritten(ex))
- split_flag = EXT4_EXT_MARK_UNWRIT1 |
- EXT4_EXT_MARK_UNWRIT2;
-
/*
* Split the extent in two so that 'end' is the last
* block in the first new extent. Also we should not
* fail removing space due to ENOSPC so try to use
* reserved block if that happens.
*/
- err = ext4_split_extent_at(handle, inode, path,
- end + 1, split_flag,
- EXT4_EX_NOCACHE |
- EXT4_GET_BLOCKS_PRE_IO |
- EXT4_GET_BLOCKS_METADATA_NOFAIL);
-
+ err = ext4_force_split_extent_at(handle, inode, path,
+ end + 1, 1);
if (err < 0)
goto out;
}
@@ -5506,3 +5509,208 @@
mutex_unlock(&inode->i_mutex);
return ret;
}
+
+/**
+ * ext4_swap_extents - Swap extents between two inodes
+ *
+ * @inode1: First inode
+ * @inode2: Second inode
+ * @lblk1: Start block for first inode
+ * @lblk2: Start block for second inode
+ * @count: Number of blocks to swap
+ * @mark_unwritten: Mark second inode's extents as unwritten after swap
+ * @erp: Pointer to save error value
+ *
+ * This helper routine does exactly what is promise "swap extents". All other
+ * stuff such as page-cache locking consistency, bh mapping consistency or
+ * extent's data copying must be performed by caller.
+ * Locking:
+ * i_mutex is held for both inodes
+ * i_data_sem is locked for write for both inodes
+ * Assumptions:
+ * All pages from requested range are locked for both inodes
+ */
+int
+ext4_swap_extents(handle_t *handle, struct inode *inode1,
+ struct inode *inode2, ext4_lblk_t lblk1, ext4_lblk_t lblk2,
+ ext4_lblk_t count, int unwritten, int *erp)
+{
+ struct ext4_ext_path *path1 = NULL;
+ struct ext4_ext_path *path2 = NULL;
+ int replaced_count = 0;
+
+ BUG_ON(!rwsem_is_locked(&EXT4_I(inode1)->i_data_sem));
+ BUG_ON(!rwsem_is_locked(&EXT4_I(inode2)->i_data_sem));
+ BUG_ON(!mutex_is_locked(&inode1->i_mutex));
+ BUG_ON(!mutex_is_locked(&inode1->i_mutex));
+
+ *erp = ext4_es_remove_extent(inode1, lblk1, count);
+ if (*erp)
+ return 0;
+ *erp = ext4_es_remove_extent(inode2, lblk2, count);
+ if (*erp)
+ return 0;
+
+ while (count) {
+ struct ext4_extent *ex1, *ex2, tmp_ex;
+ ext4_lblk_t e1_blk, e2_blk;
+ int e1_len, e2_len, len;
+ int split = 0;
+
+ path1 = ext4_ext_find_extent(inode1, lblk1, NULL, EXT4_EX_NOCACHE);
+ if (IS_ERR(path1)) {
+ *erp = PTR_ERR(path1);
+ break;
+ }
+ path2 = ext4_ext_find_extent(inode2, lblk2, NULL, EXT4_EX_NOCACHE);
+ if (IS_ERR(path2)) {
+ *erp = PTR_ERR(path2);
+ break;
+ }
+ ex1 = path1[path1->p_depth].p_ext;
+ ex2 = path2[path2->p_depth].p_ext;
+ /* Do we have somthing to swap ? */
+ if (unlikely(!ex2 || !ex1))
+ break;
+
+ e1_blk = le32_to_cpu(ex1->ee_block);
+ e2_blk = le32_to_cpu(ex2->ee_block);
+ e1_len = ext4_ext_get_actual_len(ex1);
+ e2_len = ext4_ext_get_actual_len(ex2);
+
+ /* Hole handling */
+ if (!in_range(lblk1, e1_blk, e1_len) ||
+ !in_range(lblk2, e2_blk, e2_len)) {
+ ext4_lblk_t next1, next2;
+
+ /* if hole after extent, then go to next extent */
+ next1 = ext4_ext_next_allocated_block(path1);
+ next2 = ext4_ext_next_allocated_block(path2);
+ /* If hole before extent, then shift to that extent */
+ if (e1_blk > lblk1)
+ next1 = e1_blk;
+ if (e2_blk > lblk2)
+ next2 = e1_blk;
+ /* Do we have something to swap */
+ if (next1 == EXT_MAX_BLOCKS || next2 == EXT_MAX_BLOCKS)
+ break;
+ /* Move to the rightest boundary */
+ len = next1 - lblk1;
+ if (len < next2 - lblk2)
+ len = next2 - lblk2;
+ if (len > count)
+ len = count;
+ lblk1 += len;
+ lblk2 += len;
+ count -= len;
+ goto repeat;
+ }
+
+ /* Prepare left boundary */
+ if (e1_blk < lblk1) {
+ split = 1;
+ *erp = ext4_force_split_extent_at(handle, inode1,
+ path1, lblk1, 0);
+ if (*erp)
+ break;
+ }
+ if (e2_blk < lblk2) {
+ split = 1;
+ *erp = ext4_force_split_extent_at(handle, inode2,
+ path2, lblk2, 0);
+ if (*erp)
+ break;
+ }
+ /* ext4_split_extent_at() may retult in leaf extent split,
+ * path must to be revalidated. */
+ if (split)
+ goto repeat;
+
+ /* Prepare right boundary */
+ len = count;
+ if (len > e1_blk + e1_len - lblk1)
+ len = e1_blk + e1_len - lblk1;
+ if (len > e2_blk + e2_len - lblk2)
+ len = e2_blk + e2_len - lblk2;
+
+ if (len != e1_len) {
+ split = 1;
+ *erp = ext4_force_split_extent_at(handle, inode1,
+ path1, lblk1 + len, 0);
+ if (*erp)
+ break;
+ }
+ if (len != e2_len) {
+ split = 1;
+ *erp = ext4_force_split_extent_at(handle, inode2,
+ path2, lblk2 + len, 0);
+ if (*erp)
+ break;
+ }
+ /* ext4_split_extent_at() may retult in leaf extent split,
+ * path must to be revalidated. */
+ if (split)
+ goto repeat;
+
+ BUG_ON(e2_len != e1_len);
+ *erp = ext4_ext_get_access(handle, inode1, path1 + path1->p_depth);
+ if (*erp)
+ break;
+ *erp = ext4_ext_get_access(handle, inode2, path2 + path2->p_depth);
+ if (*erp)
+ break;
+
+ /* Both extents are fully inside boundaries. Swap it now */
+ tmp_ex = *ex1;
+ ext4_ext_store_pblock(ex1, ext4_ext_pblock(ex2));
+ ext4_ext_store_pblock(ex2, ext4_ext_pblock(&tmp_ex));
+ ex1->ee_len = cpu_to_le16(e2_len);
+ ex2->ee_len = cpu_to_le16(e1_len);
+ if (unwritten)
+ ext4_ext_mark_unwritten(ex2);
+ if (ext4_ext_is_unwritten(&tmp_ex))
+ ext4_ext_mark_unwritten(ex1);
+
+ ext4_ext_try_to_merge(handle, inode2, path2, ex2);
+ ext4_ext_try_to_merge(handle, inode1, path1, ex1);
+ *erp = ext4_ext_dirty(handle, inode2, path2 +
+ path2->p_depth);
+ if (*erp)
+ break;
+ *erp = ext4_ext_dirty(handle, inode1, path1 +
+ path1->p_depth);
+ /*
+ * Looks scarry ah..? second inode already points to new blocks,
+ * and it was successfully dirtied. But luckily error may happen
+ * only due to journal error, so full transaction will be
+ * aborted anyway.
+ */
+ if (*erp)
+ break;
+ lblk1 += len;
+ lblk2 += len;
+ replaced_count += len;
+ count -= len;
+
+ repeat:
+ if (path1) {
+ ext4_ext_drop_refs(path1);
+ kfree(path1);
+ path1 = NULL;
+ }
+ if (path2) {
+ ext4_ext_drop_refs(path2);
+ kfree(path2);
+ path2 = NULL;
+ }
+ }
+ if (path1) {
+ ext4_ext_drop_refs(path1);
+ kfree(path1);
+ }
+ if (path2) {
+ ext4_ext_drop_refs(path2);
+ kfree(path2);
+ }
+ return replaced_count;
+}