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    Subject[PATCH 4.14 43/95] btrfs: property: Set incompat flag if lzo/zstd compression is set
    Date
    4.14-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Misono Tomohiro <misono.tomohiro@jp.fujitsu.com>

    commit 1a63c198ddb810c790101d693c7071cca703b3c7 upstream.

    Incompat flag of LZO/ZSTD compression should be set at:

    1. mount time (-o compress/compress-force)
    2. when defrag is done
    3. when property is set

    Currently 3. is missing and this commit adds this.

    This could lead to a filesystem that uses ZSTD but is not marked as
    such. If a kernel without a ZSTD support encounteres a ZSTD compressed
    extent, it will handle that but this could be confusing to the user.

    Typically the filesystem is mounted with the ZSTD option, but the
    discrepancy can arise when a filesystem is never mounted with ZSTD and
    then the property on some file is set (and some new extents are
    written). A simple mount with -o compress=zstd will fix that up on an
    unpatched kernel.

    Same goes for LZO, but this has been around for a very long time
    (2.6.37) so it's unlikely that a pre-LZO kernel would be used.

    Fixes: 5c1aab1dd544 ("btrfs: Add zstd support")
    CC: stable@vger.kernel.org # 4.14+
    Signed-off-by: Tomohiro Misono <misono.tomohiro@jp.fujitsu.com>
    Reviewed-by: Anand Jain <anand.jain@oracle.com>
    Reviewed-by: David Sterba <dsterba@suse.com>
    [ add user visible impact ]
    Signed-off-by: David Sterba <dsterba@suse.com>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    fs/btrfs/props.c | 12 ++++++++----
    1 file changed, 8 insertions(+), 4 deletions(-)

    --- a/fs/btrfs/props.c
    +++ b/fs/btrfs/props.c
    @@ -400,6 +400,7 @@ static int prop_compression_apply(struct
    const char *value,
    size_t len)
    {
    + struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
    int type;

    if (len == 0) {
    @@ -410,14 +411,17 @@ static int prop_compression_apply(struct
    return 0;
    }

    - if (!strncmp("lzo", value, 3))
    + if (!strncmp("lzo", value, 3)) {
    type = BTRFS_COMPRESS_LZO;
    - else if (!strncmp("zlib", value, 4))
    + btrfs_set_fs_incompat(fs_info, COMPRESS_LZO);
    + } else if (!strncmp("zlib", value, 4)) {
    type = BTRFS_COMPRESS_ZLIB;
    - else if (!strncmp("zstd", value, len))
    + } else if (!strncmp("zstd", value, len)) {
    type = BTRFS_COMPRESS_ZSTD;
    - else
    + btrfs_set_fs_incompat(fs_info, COMPRESS_ZSTD);
    + } else {
    return -EINVAL;
    + }

    BTRFS_I(inode)->flags &= ~BTRFS_INODE_NOCOMPRESS;
    BTRFS_I(inode)->flags |= BTRFS_INODE_COMPRESS;

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