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authorGao Xiang <xiang@kernel.org>2021-05-10 09:47:15 +0300
committerGao Xiang <xiang@kernel.org>2021-05-13 10:58:46 +0300
commit0852b6ca941ef3ff75076e85738877bd3271e1cd (patch)
tree776b4b7bdce0a469fb198985260af221ff188c5e /fs/erofs
parent46f2e04484aee056c97f79162da83ac7d2d621bb (diff)
downloadlinux-0852b6ca941ef3ff75076e85738877bd3271e1cd.tar.xz
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 'fs/erofs')
-rw-r--r--fs/erofs/zmap.c21
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;