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ext4: add FALLOC_FL_WRITE_ZEROES support

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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: Zhang Yi <yi.zhang@huawei.com>
Link: https://lore.kernel.org/20250619111806.3546162-10-yi.zhang@huaweicloud.com
Reviewed-by: "Martin K. Petersen" <martin.petersen@oracle.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
This commit is contained in:
Zhang Yi
2025-06-19 19:18:06 +08:00
committed by Christian Brauner
parent 912b6038fe
commit f4265b8d32
2 changed files with 57 additions and 12 deletions
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66
fs/ext4/extents.c
View File

@@ -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);

3
include/trace/events/ext4.h
View File

@@ -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);