Commit f4265b8d authored by Zhang Yi's avatar Zhang Yi Committed by Christian Brauner
Browse files

ext4: add FALLOC_FL_WRITE_ZEROES support 



Add support for FALLOC_FL_WRITE_ZEROES if the underlying device enable
the unmap write zeroes operation. This first allocates blocks as
unwritten, then issues a zero command outside of the running journal
handle, and finally converts them to a written state.

Signed-off-by: default avatarZhang Yi <yi.zhang@huawei.com>
Link: https://lore.kernel.org/20250619111806.3546162-10-yi.zhang@huaweicloud.com


Reviewed-by: default avatar"Martin K. Petersen" <martin.petersen@oracle.com>
Signed-off-by: default avatarChristian Brauner <brauner@kernel.org>
parent 912b6038

fs/ext4/extents.c

+55 −11
Original line number Diff line number Diff line
@@ -4501,6 +4501,8 @@ static int ext4_alloc_file_blocks(struct file *file, ext4_lblk_t offset, 
	struct ext4_map_blocks map;

	unsigned int credits;

	loff_t epos, old_size = i_size_read(inode);

	unsigned int blkbits = inode->i_blkbits;

	bool alloc_zero = false;



	BUG_ON(!ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS));

	map.m_lblk = offset;
@@ -4513,6 +4515,17 @@ static int ext4_alloc_file_blocks(struct file *file, ext4_lblk_t offset, 
	if (len <= EXT_UNWRITTEN_MAX_LEN)

		flags |= EXT4_GET_BLOCKS_NO_NORMALIZE;



	/*

	 * Do the actual write zero during a running journal transaction

	 * costs a lot. First allocate an unwritten extent and then

	 * convert it to written after zeroing it out.

	 */

	if (flags & EXT4_GET_BLOCKS_ZERO) {

		flags &= ~EXT4_GET_BLOCKS_ZERO;

		flags |= EXT4_GET_BLOCKS_UNWRIT_EXT;

		alloc_zero = true;

	}



	/*

	 * credits to insert 1 extent into extent tree

	 */
@@ -4549,9 +4562,7 @@ static int ext4_alloc_file_blocks(struct file *file, ext4_lblk_t offset, 
		 * allow a full retry cycle for any remaining allocations

		 */

		retries = 0;

		map.m_lblk += ret;

		map.m_len = len = len - ret;

		epos = (loff_t)map.m_lblk << inode->i_blkbits;

		epos = (loff_t)(map.m_lblk + ret) << blkbits;

		inode_set_ctime_current(inode);

		if (new_size) {

			if (epos > new_size)
@@ -4571,6 +4582,21 @@ static int ext4_alloc_file_blocks(struct file *file, ext4_lblk_t offset, 
		ret2 = ret3 ? ret3 : ret2;

		if (unlikely(ret2))

			break;



		if (alloc_zero &&

		    (map.m_flags & (EXT4_MAP_MAPPED | EXT4_MAP_UNWRITTEN))) {

			ret2 = ext4_issue_zeroout(inode, map.m_lblk, map.m_pblk,

						  map.m_len);

			if (likely(!ret2))

				ret2 = ext4_convert_unwritten_extents(NULL,

					inode, (loff_t)map.m_lblk << blkbits,

					(loff_t)map.m_len << blkbits);

			if (ret2)

				break;

		}



		map.m_lblk += ret;

		map.m_len = len = len - ret;

	}

	if (ret == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries))

		goto retry;
@@ -4636,7 +4662,11 @@ static long ext4_zero_range(struct file *file, loff_t offset, 
	if (end_lblk > start_lblk) {

		ext4_lblk_t zero_blks = end_lblk - start_lblk;



		flags |= (EXT4_GET_BLOCKS_CONVERT_UNWRITTEN | EXT4_EX_NOCACHE);

		if (mode & FALLOC_FL_WRITE_ZEROES)

			flags = EXT4_GET_BLOCKS_CREATE_ZERO | EXT4_EX_NOCACHE;

		else

			flags |= (EXT4_GET_BLOCKS_CONVERT_UNWRITTEN |

				  EXT4_EX_NOCACHE);

		ret = ext4_alloc_file_blocks(file, start_lblk, zero_blks,

					     new_size, flags);

		if (ret)
@@ -4745,11 +4775,18 @@ long ext4_fallocate(struct file *file, int mode, loff_t offset, loff_t len) 
	if (IS_ENCRYPTED(inode) &&

	    (mode & (FALLOC_FL_COLLAPSE_RANGE | FALLOC_FL_INSERT_RANGE)))

		return -EOPNOTSUPP;

	/*

	 * Don't allow writing zeroes if the underlying device does not

	 * enable the unmap write zeroes operation.

	 */

	if ((mode & FALLOC_FL_WRITE_ZEROES) &&

	    !bdev_write_zeroes_unmap_sectors(inode->i_sb->s_bdev))

		return -EOPNOTSUPP;



	/* Return error if mode is not supported */

	if (mode & ~(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE |

		     FALLOC_FL_COLLAPSE_RANGE | FALLOC_FL_ZERO_RANGE |

		     FALLOC_FL_INSERT_RANGE))

		     FALLOC_FL_ZERO_RANGE | FALLOC_FL_COLLAPSE_RANGE |

		     FALLOC_FL_INSERT_RANGE | FALLOC_FL_WRITE_ZEROES))

		return -EOPNOTSUPP;



	inode_lock(inode);
@@ -4780,16 +4817,23 @@ long ext4_fallocate(struct file *file, int mode, loff_t offset, loff_t len) 
	if (ret)

		goto out_invalidate_lock;



	if (mode & FALLOC_FL_PUNCH_HOLE)

	switch (mode & FALLOC_FL_MODE_MASK) {

	case FALLOC_FL_PUNCH_HOLE:

		ret = ext4_punch_hole(file, offset, len);

	else if (mode & FALLOC_FL_COLLAPSE_RANGE)

		break;

	case FALLOC_FL_COLLAPSE_RANGE:

		ret = ext4_collapse_range(file, offset, len);

	else if (mode & FALLOC_FL_INSERT_RANGE)

		break;

	case FALLOC_FL_INSERT_RANGE:

		ret = ext4_insert_range(file, offset, len);

	else if (mode & FALLOC_FL_ZERO_RANGE)

		break;

	case FALLOC_FL_ZERO_RANGE:

	case FALLOC_FL_WRITE_ZEROES:

		ret = ext4_zero_range(file, offset, len, mode);

	else

		break;

	default:

		ret = -EOPNOTSUPP;

	}



out_invalidate_lock:

	filemap_invalidate_unlock(mapping);

include/trace/events/ext4.h

+2 −1
Original line number Diff line number Diff line
@@ -92,7 +92,8 @@ TRACE_DEFINE_ENUM(ES_REFERENCED_B); 
	{ FALLOC_FL_KEEP_SIZE,		"KEEP_SIZE"},		\

	{ FALLOC_FL_PUNCH_HOLE,		"PUNCH_HOLE"},		\

	{ FALLOC_FL_COLLAPSE_RANGE,	"COLLAPSE_RANGE"},	\

	{ FALLOC_FL_ZERO_RANGE,		"ZERO_RANGE"})

	{ FALLOC_FL_ZERO_RANGE,		"ZERO_RANGE"},		\

	{ FALLOC_FL_WRITE_ZEROES,	"WRITE_ZEROES"})



TRACE_DEFINE_ENUM(EXT4_FC_REASON_XATTR);

TRACE_DEFINE_ENUM(EXT4_FC_REASON_CROSS_RENAME);