[PATCH 1/2] erofs-utils: don't reuse full mapped buffer blocks

[Gao Xiang via Linux-erofs]

From: Gao Xiang <hsiang...@aol.com>

Otherwise it could cause data corruption since erofs_battach()
doesn't support full buffer blocks (and oob would be misjudged.)

Fixes: 185b0bcdef4b ("erofs-utils: optimize buffer allocation logic")
Signed-off-by: Gao Xiang <hsiang...@aol.com>
---
 lib/cache.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/lib/cache.c b/lib/cache.c
index 40d3b1f3f4d5..e8840ac5dd31 100644
--- a/lib/cache.c
+++ b/lib/cache.c
@@ -155,8 +155,8 @@ static int erofs_bfind_for_attach(int type, erofs_off_t 
size,
                                  struct erofs_buffer_block **bbp)
 {
        struct erofs_buffer_block *cur, *bb;
-       unsigned int used0, usedmax, used;
-       int used_before, ret;
+       unsigned int used0, used_before, usedmax, used;
+       int ret;
 
        used0 = (size + required_ext) % EROFS_BLKSIZ + inline_ext;
        /* inline data should be in the same fs block */
@@ -177,7 +177,7 @@ static int erofs_bfind_for_attach(int type, erofs_off_t 
size,
 
        used_before = rounddown(EROFS_BLKSIZ -
                                (size + required_ext + inline_ext), alignsize);
-       do {
+       for (; used_before; --used_before) {
                struct list_head *bt = mapped_buckets[type] + used_before;
 
                if (list_empty(bt))
@@ -203,7 +203,7 @@ static int erofs_bfind_for_attach(int type, erofs_off_t 
size,
                bb = cur;
                usedmax = used;
                break;
-       } while (--used_before > 0);
+       }
 
 skip_mapped:
        /* try to start from the last mapped one, which can be expended */
-- 
2.24.0