bcachefs: fix bch2_rbio_narrow_crcs()

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

diff --git a/fs/bcachefs/io.c b/fs/bcachefs/io.c
index b07b0f92d4f9130d7869c692ef3b4e0b26856b8a..9bb4b1fe5b8a02f8812b9aeba5342fb86c37edc2 100644 (file)
--- a/fs/bcachefs/io.c
+++ b/fs/bcachefs/io.c
@@ -1422,7 +1422,7 @@ static void bch2_rbio_narrow_crcs(struct bch_read_bio *rbio)
        struct bkey_i_extent *e;
        BKEY_PADDED(k) new;
        struct bch_extent_crc_unpacked new_crc;
-       unsigned offset;
+       u64 data_offset = rbio->pos.offset - rbio->pick.crc.offset;
        int ret;
 
        if (rbio->pick.crc.compression_type)
@@ -1445,24 +1445,19 @@ retry:
        e = bkey_i_to_extent(&new.k);
 
        if (!bch2_extent_matches_ptr(c, extent_i_to_s_c(e),
-                                    rbio->pick.ptr,
-                                    rbio->pos.offset -
-                                    rbio->pick.crc.offset) ||
+                                    rbio->pick.ptr, data_offset) ||
            bversion_cmp(e->k.version, rbio->version))
                goto out;
 
        /* Extent was merged? */
-       if (bkey_start_offset(&e->k) < rbio->pos.offset ||
-           e->k.p.offset > rbio->pos.offset + rbio->pick.crc.uncompressed_size)
+       if (bkey_start_offset(&e->k) < data_offset ||
+           e->k.p.offset > data_offset + rbio->pick.crc.uncompressed_size)
                goto out;
 
-       /* The extent might have been partially overwritten since we read it: */
-       offset = rbio->pick.crc.offset + (bkey_start_offset(&e->k) - rbio->pos.offset);
-
        if (bch2_rechecksum_bio(c, &rbio->bio, rbio->version,
-                               rbio->pick.crc, NULL, &new_crc,
-                               offset, e->k.size,
-                               rbio->pick.crc.csum_type)) {
+                       rbio->pick.crc, NULL, &new_crc,
+                       bkey_start_offset(&e->k) - data_offset, e->k.size,
+                       rbio->pick.crc.csum_type)) {
                bch_err(c, "error verifying existing checksum while narrowing checksum (memory corruption?)");
                goto out;
        }