udf: allow implicit blocksize specification during mount

udf_fill_super() used udf_parse_options() to flag UDF_FLAG_BLOCKSIZE_SET
when blocksize was specified otherwise used 512 bytes
(bdev_logical_block_size) and 2048 bytes (UDF_DEFAULT_BLOCKSIZE)
IOW both 1024 and 4096 specifications were required or resulted in

"mount: wrong fs type, bad option, bad superblock on /dev/loop1"

This patch loops through different block values but also updates
udf_load_vrs() to return -EINVAL instead of 0 when udf_check_vsd()
fails (and uopt->novrs = 0).
The later being the reason for the RFC; we have that case when mounting
a 4kb blocksize against other values but maybe VRS is not mandatory
there ?

Tested with 512, 1024, 2048 and 4096 blocksize

Reported-by: Jan Kara <jack@suse.com>
Signed-off-by: Fabian Frederick <fabf@skynet.be>
Signed-off-by: Jan Kara <jack@suse.cz>

diff --git a/fs/udf/super.c b/fs/udf/super.c
index 6b5a1a4..14b4bc1 100644 (file)
--- a/fs/udf/super.c
+++ b/fs/udf/super.c
@@ -1955,7 +1955,7 @@ static int udf_load_vrs(struct super_block *sb, struct udf_options *uopt,
                if (!nsr_off) {
                        if (!silent)
                                udf_warn(sb, "No VRS found\n");
-                       return 0;
+                       return -EINVAL;
                }
                if (nsr_off == -1)
                        udf_debug("Failed to read sector at offset %d. "
@@ -2159,15 +2159,25 @@ static int udf_fill_super(struct super_block *sb, void *options, int silent)
                ret = udf_load_vrs(sb, &uopt, silent, &fileset);
        } else {
                uopt.blocksize = bdev_logical_block_size(sb->s_bdev);
-               ret = udf_load_vrs(sb, &uopt, silent, &fileset);
-               if (ret == -EAGAIN && uopt.blocksize != UDF_DEFAULT_BLOCKSIZE) {
-                       if (!silent)
-                               pr_notice("Rescanning with blocksize %d\n",
-                                         UDF_DEFAULT_BLOCKSIZE);
-                       brelse(sbi->s_lvid_bh);
-                       sbi->s_lvid_bh = NULL;
-                       uopt.blocksize = UDF_DEFAULT_BLOCKSIZE;
+               while (uopt.blocksize <= 4096) {
                        ret = udf_load_vrs(sb, &uopt, silent, &fileset);
+                       if (ret < 0) {
+                               if (!silent && ret != -EACCES) {
+                                       pr_notice("Scanning with blocksize %d failed\n",
+                                                 uopt.blocksize);
+                               }
+                               brelse(sbi->s_lvid_bh);
+                               sbi->s_lvid_bh = NULL;
+                               /*
+                                * EACCES is special - we want to propagate to
+                                * upper layers that we cannot handle RW mount.
+                                */
+                               if (ret == -EACCES)
+                                       break;
+                       } else
+                               break;
+
+                       uopt.blocksize <<= 1;
                }
        }
        if (ret < 0) {