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ext4: ensure zeroed partial blocks are persisted in SYNC mode

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In ext4_zero_range() and ext4_punch_hole(), when operating in SYNC mode
and zeroing a partial block, only data=journal modes guarantee that the
zeroed data is synchronously persisted after the operation completes.
For data=ordered/writeback mode and non-journal modes, this guarantee is
missing.

Introduce a partial_zero parameter to explicitly trigger writeback for
all scenarios where a partial block is zeroed, ensuring the zeroed data
is durably persisted.

Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
Link: https://patch.msgid.link/20260327102939.1095257-10-yi.zhang@huaweicloud.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
This commit is contained in:
Zhang Yi
2026-03-27 18:29:35 +08:00
committed by Theodore Ts'o
parent c4602a1d09
commit 7d81ec0246
3 changed files with 23 additions and 7 deletions
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2
fs/ext4/ext4.h
View File

@@ -3099,7 +3099,7 @@ extern int ext4_meta_trans_blocks(struct inode *inode, int lblocks,
int pextents);
extern int ext4_block_zero_eof(struct inode *inode, loff_t from, loff_t end);
extern int ext4_zero_partial_blocks(struct inode *inode, loff_t lstart,
loff_t length);
loff_t length, bool *did_zero);
extern vm_fault_t ext4_page_mkwrite(struct vm_fault *vmf);
extern qsize_t *ext4_get_reserved_space(struct inode *inode);
extern int ext4_get_projid(struct inode *inode, kprojid_t *projid);

9
fs/ext4/extents.c
View File

@@ -4702,6 +4702,7 @@ static long ext4_zero_range(struct file *file, loff_t offset,
loff_t align_start, align_end, new_size = 0;
loff_t end = offset + len;
unsigned int blocksize = i_blocksize(inode);
bool partial_zeroed = false;
int ret, flags;
trace_ext4_zero_range(inode, offset, len, mode);
@@ -4757,9 +4758,15 @@ static long ext4_zero_range(struct file *file, loff_t offset,
return ret;
/* Zero out partial block at the edges of the range */
ret = ext4_zero_partial_blocks(inode, offset, len);
ret = ext4_zero_partial_blocks(inode, offset, len, &partial_zeroed);
if (ret)
return ret;
if (((file->f_flags & O_SYNC) || IS_SYNC(inode)) && partial_zeroed) {
ret = filemap_write_and_wait_range(inode->i_mapping, offset,
end - 1);
if (ret)
return ret;
}
handle = ext4_journal_start(inode, EXT4_HT_MISC, 1);
if (IS_ERR(handle)) {

19
fs/ext4/inode.c
View File

@@ -4257,7 +4257,8 @@ int ext4_block_zero_eof(struct inode *inode, loff_t from, loff_t end)
return 0;
}
int ext4_zero_partial_blocks(struct inode *inode, loff_t lstart, loff_t length)
int ext4_zero_partial_blocks(struct inode *inode, loff_t lstart, loff_t length,
bool *did_zero)
{
struct super_block *sb = inode->i_sb;
unsigned partial_start, partial_end;
@@ -4274,20 +4275,21 @@ int ext4_zero_partial_blocks(struct inode *inode, loff_t lstart, loff_t length)
/* Handle partial zero within the single block */
if (start == end &&
(partial_start || (partial_end != sb->s_blocksize - 1))) {
err = ext4_block_zero_range(inode, lstart, length, NULL, NULL);
err = ext4_block_zero_range(inode, lstart, length, did_zero,
NULL);
return err;
}
/* Handle partial zero out on the start of the range */
if (partial_start) {
err = ext4_block_zero_range(inode, lstart, sb->s_blocksize,
NULL, NULL);
did_zero, NULL);
if (err)
return err;
}
/* Handle partial zero out on the end of the range */
if (partial_end != sb->s_blocksize - 1)
err = ext4_block_zero_range(inode, byte_end - partial_end,
partial_end + 1, NULL, NULL);
partial_end + 1, did_zero, NULL);
return err;
}
@@ -4436,6 +4438,7 @@ int ext4_punch_hole(struct file *file, loff_t offset, loff_t length)
loff_t end = offset + length;
handle_t *handle;
unsigned int credits;
bool partial_zeroed = false;
int ret;
trace_ext4_punch_hole(inode, offset, length, 0);
@@ -4471,9 +4474,15 @@ int ext4_punch_hole(struct file *file, loff_t offset, loff_t length)
if (ret)
return ret;
ret = ext4_zero_partial_blocks(inode, offset, length);
ret = ext4_zero_partial_blocks(inode, offset, length, &partial_zeroed);
if (ret)
return ret;
if (((file->f_flags & O_SYNC) || IS_SYNC(inode)) && partial_zeroed) {
ret = filemap_write_and_wait_range(inode->i_mapping, offset,
end - 1);
if (ret)
return ret;
}
if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
credits = ext4_chunk_trans_extent(inode, 0);