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Commit f2754114 authored by Eric Sandeen's avatar Eric Sandeen Committed by Theodore Ts'o
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ext4: remove unreachable code after ext4_can_extents_be_merged() 



Commit ec22ba8e ("ext4: disable merging of uninitialized extents")
ensured that if either extent under consideration is uninit, we
decline to merge, and ext4_can_extents_be_merged() returns false.

So there is no need for the caller to then test whether the
extent under consideration is unitialized; if it were, we
wouldn't have gotten that far.

The comments were also inaccurate; ext4_can_extents_be_merged()
no longer XORs the states, it fails if *either* is uninit.

Signed-off-by: default avatarEric Sandeen <sandeen@redhat.com>
Signed-off-by: default avatar"Theodore Ts'o" <tytso@mit.edu>
Reviewed-by: default avatarZheng Liu <wenqing.lz@taobao.com>
parent da0169b3

fs/ext4/extents.c

+0 −26
Original line number Diff line number Diff line
@@ -1715,7 +1715,6 @@ static int ext4_ext_try_to_merge_right(struct inode *inode, 
	struct ext4_extent_header *eh;

	unsigned int depth, len;

	int merge_done = 0;

	int uninitialized = 0;



	depth = ext_depth(inode);

	BUG_ON(path[depth].p_hdr == NULL);
@@ -1725,12 +1724,8 @@ static int ext4_ext_try_to_merge_right(struct inode *inode, 
		if (!ext4_can_extents_be_merged(inode, ex, ex + 1))

			break;

		/* merge with next extent! */

		if (ext4_ext_is_uninitialized(ex))

			uninitialized = 1;

		ex->ee_len = cpu_to_le16(ext4_ext_get_actual_len(ex)

				+ ext4_ext_get_actual_len(ex + 1));

		if (uninitialized)

			ext4_ext_mark_uninitialized(ex);



		if (ex + 1 < EXT_LAST_EXTENT(eh)) {

			len = (EXT_LAST_EXTENT(eh) - ex - 1)
@@ -1885,7 +1880,6 @@ int ext4_ext_insert_extent(handle_t *handle, struct inode *inode, 
	struct ext4_ext_path *npath = NULL;

	int depth, len, err;

	ext4_lblk_t next;

	unsigned uninitialized = 0;

	int mb_flags = 0;



	if (unlikely(ext4_ext_get_actual_len(newext) == 0)) {
@@ -1937,18 +1931,8 @@ int ext4_ext_insert_extent(handle_t *handle, struct inode *inode, 
			if (err)

				return err;



			/*

			 * ext4_can_extents_be_merged should have checked

			 * that either both extents are uninitialized, or

			 * both aren't. Thus we need to check only one of

			 * them here.

			 */

			if (ext4_ext_is_uninitialized(ex))

				uninitialized = 1;

			ex->ee_len = cpu_to_le16(ext4_ext_get_actual_len(ex)

					+ ext4_ext_get_actual_len(newext));

			if (uninitialized)

				ext4_ext_mark_uninitialized(ex);

			eh = path[depth].p_hdr;

			nearex = ex;

			goto merge;
@@ -1971,20 +1955,10 @@ int ext4_ext_insert_extent(handle_t *handle, struct inode *inode, 
			if (err)

				return err;



			/*

			 * ext4_can_extents_be_merged should have checked

			 * that either both extents are uninitialized, or

			 * both aren't. Thus we need to check only one of

			 * them here.

			 */

			if (ext4_ext_is_uninitialized(ex))

				uninitialized = 1;

			ex->ee_block = newext->ee_block;

			ext4_ext_store_pblock(ex, ext4_ext_pblock(newext));

			ex->ee_len = cpu_to_le16(ext4_ext_get_actual_len(ex)

					+ ext4_ext_get_actual_len(newext));

			if (uninitialized)

				ext4_ext_mark_uninitialized(ex);

			eh = path[depth].p_hdr;

			nearex = ex;

			goto merge;