On 07/18/2017 12:22 AM, David Sterba wrote:
This is a minimal patch intended to be backported to older kernels.
We're going to extend the string specifying the compression method and
this would fail on kernels before that change (the string is compared
exactly).
Relax the string matching only to the prefix, ie. ignoring anything that
goes after "zlib" or "lzo", regardless of th format extension we decide
to use. This applies to the mount options and properties.
That way, patched old kernels could be booted on systems already
utilizing the new compression spec.
In the view of older kernel with this patch, we need extra logic to
continue to fail bad string after lzo..
----
mount -o compress=lzoJUNK /dev/sdb /btrfs
mount: wrong fs type, bad option, bad superblock on /dev/sdb,
[ 2128.045252] BTRFS error (device sdb): open_ctree failed
----
With this patch. I guess the above mount (or for that matter property
as well) will be successful. ?
Thanks, Anand
Applicable since commit 63541927c8d11, v3.14.
Signed-off-by: David Sterba <dste...@suse.com>
---
fs/btrfs/props.c | 4 ++--
fs/btrfs/super.c | 4 ++--
2 files changed, 4 insertions(+), 4 deletions(-)
diff --git a/fs/btrfs/props.c b/fs/btrfs/props.c
index 4b23ae5d0e5c..f41654f05719 100644
--- a/fs/btrfs/props.c
+++ b/fs/btrfs/props.c
@@ -408,9 +408,9 @@ static int prop_compression_apply(struct inode *inode,
return 0;
}
- if (!strncmp("lzo", value, len))
+ if (!strncmp("lzo", value, 3))
type = BTRFS_COMPRESS_LZO;
- else if (!strncmp("zlib", value, len))
+ else if (!strncmp("zlib", value, 4))
type = BTRFS_COMPRESS_ZLIB;
else
return -EINVAL;
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 74e47794e63f..147330454c17 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -498,14 +498,14 @@ int btrfs_parse_options(struct btrfs_fs_info *info, char
*options,
btrfs_test_opt(info, FORCE_COMPRESS);
if (token == Opt_compress ||
token == Opt_compress_force ||
- strcmp(args[0].from, "zlib") == 0) {
+ strncmp(args[0].from, "zlib", 4) == 0) {
compress_type = "zlib";
info->compress_type = BTRFS_COMPRESS_ZLIB;
btrfs_set_opt(info->mount_opt, COMPRESS);
btrfs_clear_opt(info->mount_opt, NODATACOW);
btrfs_clear_opt(info->mount_opt, NODATASUM);
no_compress = 0;
- } else if (strcmp(args[0].from, "lzo") == 0) {
+ } else if (strncmp(args[0].from, "lzo", 3) == 0) {
compress_type = "lzo";
info->compress_type = BTRFS_COMPRESS_LZO;
btrfs_set_opt(info->mount_opt, COMPRESS);
--
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