ext4: punch hole optimizations: skip un-needed extent lookup (f7d0d379) · Commits · 戴 / test

This patch optimizes the punch hole operation by skipping the tree walking code that is used by truncate. Since punch hole is done through map blocks, the path to the extent is already known in this function, so we do not need to look it up again. Signed-off-by:

Allison Henderson <achender@linux.vnet.ibm.com> Signed-off-by:

"Theodore Ts'o" <tytso@mit.edu>

fs/ext4/extents.c

+21 −2

Original line number	Diff line number	Diff line
		@@ -3461,8 +3461,27 @@ int ext4_ext_map_blocks(handle_t handle, struct inode inode,

		ext4_ext_mark_uninitialized(ex);

		err = ext4_ext_remove_space(inode, map->m_lblk,
		map->m_lblk + punched_out);
		ext4_ext_invalidate_cache(inode);

		err = ext4_ext_rm_leaf(handle, inode, path,
		map->m_lblk, map->m_lblk + punched_out);

		if (!err && path->p_hdr->eh_entries == 0) {
		/*
		* Punch hole freed all of this sub tree,
		* so we need to correct eh_depth
		*/
		err = ext4_ext_get_access(handle, inode, path);
		if (err == 0) {
		ext_inode_hdr(inode)->eh_depth = 0;
		ext_inode_hdr(inode)->eh_max =
		cpu_to_le16(ext4_ext_space_root(
		inode, 0));

		err = ext4_ext_dirty(
		handle, inode, path);
		}
		}

		goto out2;
		}

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