From 50dbfd9dacda52ae3f891062ec48f8daa536b26a Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Wed, 29 Mar 2023 09:13:05 +0900 Subject: [PATCH] btrfs: fix fast csum implementation detection commit 68d99ab0e9221ef54506f827576c5a914680eeaf upstream. The BTRFS_FS_CSUM_IMPL_FAST flag is currently set whenever a non-generic crc32c is detected, which is the incorrect check if the file system uses a different checksumming algorithm. Refactor the code to only check this if crc32c is actually used. Note that in an ideal world the information if an algorithm is hardware accelerated or not should be provided by the crypto API instead, but that's left for another day. CC: stable@vger.kernel.org # 5.4.x: c8a5f8ca9a9c: btrfs: print checksum type and implementation at mount time CC: stable@vger.kernel.org # 5.4.x Signed-off-by: Christoph Hellwig Reviewed-by: David Sterba Signed-off-by: David Sterba Signed-off-by: Greg Kroah-Hartman --- fs/btrfs/disk-io.c | 14 ++++++++++++++ fs/btrfs/super.c | 2 -- 2 files changed, 14 insertions(+), 2 deletions(-) diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c index 80b8f03161c5..4536d8aea196 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -2239,6 +2239,20 @@ static int btrfs_init_csum_hash(struct btrfs_fs_info *fs_info, u16 csum_type) fs_info->csum_shash = csum_shash; + /* + * Check if the checksum implementation is a fast accelerated one. + * As-is this is a bit of a hack and should be replaced once the csum + * implementations provide that information themselves. + */ + switch (csum_type) { + case BTRFS_CSUM_TYPE_CRC32: + if (!strstr(crypto_shash_driver_name(csum_shash), "generic")) + set_bit(BTRFS_FS_CSUM_IMPL_FAST, &fs_info->flags); + break; + default: + break; + } + btrfs_info(fs_info, "using %s (%s) checksum algorithm", btrfs_super_csum_name(csum_type), crypto_shash_driver_name(csum_shash)); diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c index 1a69bdb96fb2..8d21019bbbab 100644 --- a/fs/btrfs/super.c +++ b/fs/btrfs/super.c @@ -1567,8 +1567,6 @@ static struct dentry *btrfs_mount_root(struct file_system_type *fs_type, } else { snprintf(s->s_id, sizeof(s->s_id), "%pg", bdev); btrfs_sb(s)->bdev_holder = fs_type; - if (!strstr(crc32c_impl(), "generic")) - set_bit(BTRFS_FS_CSUM_IMPL_FAST, &fs_info->flags); error = btrfs_fill_super(s, fs_devices, data); } if (!error)