From: Al Viro Date: Thu, 18 Apr 2024 04:21:25 +0000 (-0400) Subject: btrfs_get_bdev_and_sb(): call set_blocksize() only for exclusive opens X-Git-Tag: io_uring-6.10-20240523~11^2~2 X-Git-Url: https://git.kernel.dk/?a=commitdiff_plain;h=b85c42981ac4abeeb15d16437c40f52a8a64787d;p=linux-block.git btrfs_get_bdev_and_sb(): call set_blocksize() only for exclusive opens btrfs_get_bdev_and_sb() has two callers - btrfs_open_one_device(), which asks for open to be exclusive and btrfs_get_dev_args_from_path(), which doesn't. Currently it does set_blocksize() in all cases. I'm rather dubious about the need to do set_blocksize() anywhere in btrfs, to be honest - there's some access to page cache of underlying block devices in there, but it's nowhere near the hot paths, AFAICT. In any case, btrfs_get_dev_args_from_path() only needs to read the on-disk superblock and copy several fields out of it; all callers are only interested in devices that are already opened and brought into per-filesystem set, so setting the block size is redundant for those and actively harmful if we are given a pathname of unrelated device. So we only need btrfs_get_bdev_and_sb() to call set_blocksize() when it's asked to open exclusive. Reviewed-by: Christoph Hellwig Reviewed-by: Christian Brauner Signed-off-by: Al Viro --- diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c index f15591f3e54f..43af5a9fb547 100644 --- a/fs/btrfs/volumes.c +++ b/fs/btrfs/volumes.c @@ -482,10 +482,12 @@ btrfs_get_bdev_and_sb(const char *device_path, blk_mode_t flags, void *holder, if (flush) sync_blockdev(bdev); - ret = set_blocksize(bdev, BTRFS_BDEV_BLOCKSIZE); - if (ret) { - fput(*bdev_file); - goto error; + if (holder) { + ret = set_blocksize(bdev, BTRFS_BDEV_BLOCKSIZE); + if (ret) { + fput(*bdev_file); + goto error; + } } invalidate_bdev(bdev); *disk_super = btrfs_read_dev_super(bdev); @@ -498,6 +500,7 @@ btrfs_get_bdev_and_sb(const char *device_path, blk_mode_t flags, void *holder, return 0; error: + *disk_super = NULL; *bdev_file = NULL; return ret; }