Hi all,
On 2026/7/21 14:55, zhaoyifan (H) wrote:
On 2026/7/20 19:42, Zhiguo Niu wrote:
Yifan Zhao <[email protected]> 于2026年7月9日周四 20:36写道：
With ztailpacking, the final compressed pcluster is first stored as
inline data. If the inode metadata area cannot hold it, mkfs falls back
to a normal tail block and drops the inline pcluster marker.
The current fallback path assumes that the inline tail pcluster belongs
to the EOF lcluster. That is not always true: the tail pcluster can
start in the previous lcluster and end at EOF, while its raw size still
fits in one block. In that case, patching the EOF lcluster is
semantically wrong.
Let's keep raw tail data whenever it fits in one block, and convert the
corresponding lcluster index to PLAIN during fallback.
Reported-by: Alberto Salvia Novella <[email protected]>
Closes: https://github.com/erofs/erofs-utils/issues/51
Assisted-by: Codex:GPT-5.5
Signed-off-by: Yifan Zhao <[email protected]>
---
Hi Yifan,
I tested this patch to focus on the issue fixed by commit
277a42502a7a, and it passed.
But I have some questions:
include/erofs/internal.h | 5 +-
lib/compress.c | 109 ++++++++++++++++++++++++++++-----------
2 files changed, 83 insertions(+), 31 deletions(-)
diff --git a/include/erofs/internal.h b/include/erofs/internal.h
index 2cc9cc8..bdde41f 100644
--- a/include/erofs/internal.h
+++ b/include/erofs/internal.h
@@ -212,8 +212,11 @@ struct erofs_diskbuf;
enum erofs_idata_type {
EROFS_IDATA_TYPE_RAW,
- EROFS_IDATA_TYPE_COMPRESSED_DEFAULT,
+ EROFS_IDATA_TYPE_COMPRESSED,
+ /* compressed idata follows a final 2B compacted index pack */
EROFS_IDATA_TYPE_COMPRESSED_END_OF_2B,
+ /* compressed idata follows a final single-entry 4B pack after a 2B
pack */
+ EROFS_IDATA_TYPE_COMPRESSED_4B1_PREV2B,
};
#define EROFS_I_BLKADDR_DEV_ID_BIT 48
diff --git a/lib/compress.c b/lib/compress.c
index f7ad5a1..ec90f65 100644
--- a/lib/compress.c
+++ b/lib/compress.c
@@ -483,7 +483,7 @@ static int z_erofs_fill_inline_data(struct erofs_inode
*inode, void *data,
{
inode->z_advise |= Z_EROFS_ADVISE_INLINE_PCLUSTER;
inode->idata_size = len;
- inode->idata_type = EROFS_IDATA_TYPE_COMPRESSED_DEFAULT;
+ inode->idata_type = EROFS_IDATA_TYPE_COMPRESSED;
inode->idata = malloc(inode->idata_size);
if (!inode->idata)
@@ -664,7 +664,7 @@ frag_packing:
ictx->fragemitted = true;
/* tailpcluster should be less than 1 block */
} else if (may_inline && len == e->length && compressedsize < blksz) {
- if (ctx->clusterofs + len <= blksz) {
Shouldn't this condition restrict the `tail pcluster` so that it
corresponds to only eof`lcluster`?
and we drop the inline pcluster just when eof_tailraw is not null.
Thanks!
Hi Zhiguo,
A tail pcluster may start in the previous lcluster and end in the EOF lcluster while its
whole raw payload still fits in one physical block. In that case `ctx->clusterofs +
len > blksz`, but `len <= blksz`, but it should still be converted into a single
PLAIN pcluster.
This patch targets this edge case so I think change the if statement here is
necessary?
This case has been resolved on the kernel side, so before we
get a cleaner way, let's keep this as-is since it's not a
new case for many year.
Thanks,
Gao Xiang
Thanks,
Yifan
