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ntfs: punch all-zero compressed blocks

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When a rewritten compression block consists entirely of zeroes,
ntfs_write_cb() returns without replacing its existing runlist mapping.
The old on-disk contents therefore remain visible after cache eviction.

Punch the compression unit so that reads resolve it as a sparse block and
release any clusters that held the previous contents.

Reviewed-by: Hyunchul Lee <hyc.lee@gmail.com>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
This commit is contained in:
Namjae Jeon 2026-07-20 17:43:15 +09:00
parent f2b2aeeaad
commit 2bd734ee2c
1 changed files with 6 additions and 4 deletions
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10
fs/ntfs/compress.c
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@ -1279,9 +1279,10 @@ static int ntfs_write_cb(struct ntfs_inode *ni, loff_t pos, struct page **pages,
int i, err;
int pages_count = (round_up(ni->itype.compressed.block_size + 2 *
(ni->itype.compressed.block_size / NTFS_SB_SIZE) + 2, PAGE_SIZE)) / PAGE_SIZE;
u32 cb_clusters = ni->itype.compressed.block_clusters;
size_t new_rl_count;
struct bio *bio = NULL;
loff_t new_length;
loff_t cb_pos, new_length;
s64 new_vcn;
in_mapping = vmap(pages, pages_per_cb, VM_MAP, PAGE_KERNEL_RO);
@ -1351,6 +1352,9 @@ static int ntfs_write_cb(struct ntfs_inode *ni, loff_t pos, struct page **pages,
}
}
cb_pos = pos & ~((loff_t)ni->itype.compressed.block_size - 1);
new_vcn = ntfs_bytes_to_cluster(vol, cb_pos);
if (!fail && !allzeroes) {
outbuf[compsz++] = 0;
outbuf[compsz++] = 0;
@ -1359,7 +1363,7 @@ static int ntfs_write_cb(struct ntfs_inode *ni, loff_t pos, struct page **pages,
bio_size = rounded;
pages = pages_disk;
} else if (allzeroes) {
err = 0;
err = ntfs_non_resident_attr_punch_hole(ni, new_vcn, cb_clusters);
goto out;
} else {
memcpy(outbuf, inbuf, insz);
@ -1367,8 +1371,6 @@ static int ntfs_write_cb(struct ntfs_inode *ni, loff_t pos, struct page **pages,
pages = pages_disk;
}
new_vcn = ntfs_bytes_to_cluster(vol,
pos & ~((loff_t)ni->itype.compressed.block_size - 1));
new_length = ntfs_bytes_to_cluster(vol, round_up(bio_size, vol->cluster_size));
err = ntfs_non_resident_attr_punch_hole(ni, new_vcn, ni->itype.compressed.block_clusters);