diff options
| author | Gao Xiang <xiang@kernel.org> | 2021-05-10 08:47:15 +0200 |
|---|---|---|
| committer | Gao Xiang <xiang@kernel.org> | 2021-05-13 09:58:46 +0200 |
| commit | 0852b6ca941ef3ff75076e85738877bd3271e1cd (patch) | |
| tree | 776b4b7bdce0a469fb198985260af221ff188c5e /fs/erofs/zmap.c | |
| parent | erofs: update documentation about data compression (diff) | |
| download | linux-0852b6ca941ef3ff75076e85738877bd3271e1cd.tar.xz linux-0852b6ca941ef3ff75076e85738877bd3271e1cd.zip | |
erofs: fix 1 lcluster-sized pcluster for big pcluster
If the 1st NONHEAD lcluster of a pcluster isn't CBLKCNT lcluster type
rather than a HEAD or PLAIN type instead, which means its pclustersize
_must_ be 1 lcluster (since its uncompressed size < 2 lclusters),
as illustrated below:
HEAD HEAD / PLAIN lcluster type
____________ ____________
|_:__________|_________:__| file data (uncompressed)
. .
.____________.
|____________| pcluster data (compressed)
Such on-disk case was explained before [1] but missed to be handled
properly in the runtime implementation.
It can be observed if manually generating 1 lcluster-sized pcluster
with 2 lclusters (thus CBLKCNT doesn't exist.) Let's fix it now.
[1] https://lore.kernel.org/r/20210407043927.10623-1-xiang@kernel.org
Link: https://lore.kernel.org/r/20210510064715.29123-1-xiang@kernel.org
Fixes: cec6e93beadf ("erofs: support parsing big pcluster compress indexes")
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Gao Xiang <xiang@kernel.org>
Diffstat (limited to '')
| -rw-r--r-- | fs/erofs/zmap.c | 21 |
1 files changed, 19 insertions, 2 deletions
diff --git a/fs/erofs/zmap.c b/fs/erofs/zmap.c index e62d813756f2..efaf32596b97 100644 --- a/fs/erofs/zmap.c +++ b/fs/erofs/zmap.c @@ -450,14 +450,31 @@ static int z_erofs_get_extent_compressedlen(struct z_erofs_maprecorder *m, lcn = m->lcn + 1; if (m->compressedlcs) goto out; - if (lcn == initial_lcn) - goto err_bonus_cblkcnt; err = z_erofs_load_cluster_from_disk(m, lcn); if (err) return err; + /* + * If the 1st NONHEAD lcluster has already been handled initially w/o + * valid compressedlcs, which means at least it mustn't be CBLKCNT, or + * an internal implemenatation error is detected. + * + * The following code can also handle it properly anyway, but let's + * BUG_ON in the debugging mode only for developers to notice that. + */ + DBG_BUGON(lcn == initial_lcn && + m->type == Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD); + switch (m->type) { + case Z_EROFS_VLE_CLUSTER_TYPE_PLAIN: + case Z_EROFS_VLE_CLUSTER_TYPE_HEAD: + /* + * if the 1st NONHEAD lcluster is actually PLAIN or HEAD type + * rather than CBLKCNT, it's a 1 lcluster-sized pcluster. + */ + m->compressedlcs = 1; + break; case Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD: if (m->delta[0] != 1) goto err_bonus_cblkcnt; |