From: Johannes Thumshirn <johannes.thumshirn@wdc.com>
To: David Sterba <dsterba@suse.cz>
Cc: "linux-btrfs @ vger . kernel . org" <linux-btrfs@vger.kernel.org>,
Johannes Thumshirn <johannes.thumshirn@wdc.com>,
Christoph Hellwig <hch@lst.de>
Subject: [PATCH v7 2/8] btrfs: don't kmap() pages from block devices
Date: Wed, 12 Feb 2020 16:16:58 +0900 [thread overview]
Message-ID: <20200212071704.17505-3-johannes.thumshirn@wdc.com> (raw)
In-Reply-To: <20200212071704.17505-1-johannes.thumshirn@wdc.com>
Block device mappings are never in highmem so kmap() / kunmap() calls for
pages from block devices are unneeded. Use page_address() instead of
kmap() to get to the virtual addreses.
While we're at it, read_cache_page_gfp() doesn't return NULL on error,
only an ERR_PTR, so use IS_ERR() to check for errors.
Suggested-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
---
fs/btrfs/volumes.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 6ebdd95b798d..620794f1ea64 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -1249,7 +1249,6 @@ int btrfs_open_devices(struct btrfs_fs_devices *fs_devices,
void btrfs_release_disk_super(struct page *page)
{
- kunmap(page);
put_page(page);
}
@@ -1277,10 +1276,10 @@ static int btrfs_read_disk_super(struct block_device *bdev, u64 bytenr,
*page = read_cache_page_gfp(bdev->bd_inode->i_mapping,
index, GFP_KERNEL);
- if (IS_ERR_OR_NULL(*page))
+ if (IS_ERR(*page))
return 1;
- p = kmap(*page);
+ p = page_address(*page);
/* align our pointer to the offset of the super block */
*disk_super = p + offset_in_page(bytenr);
--
2.24.1
next prev parent reply other threads:[~2020-02-12 7:17 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-12 7:16 [PATCH v7 0/8] btrfs: remove buffer heads form superblock handling Johannes Thumshirn
2020-02-12 7:16 ` [PATCH v7 1/8] btrfs: Export btrfs_release_disk_super Johannes Thumshirn
2020-02-12 7:16 ` Johannes Thumshirn [this message]
2020-02-12 7:25 ` [PATCH v7 2/8] btrfs: don't kmap() pages from block devices Christoph Hellwig
2020-02-12 7:16 ` [PATCH v7 3/8] btrfs: unexport btrfs_scratch_superblocks Johannes Thumshirn
2020-02-12 7:27 ` Christoph Hellwig
2020-02-12 7:51 ` Johannes Thumshirn
2020-02-12 7:17 ` [PATCH v7 4/8] btrfs: use the page-cache for super block reading Johannes Thumshirn
2020-02-12 7:28 ` Christoph Hellwig
2020-02-12 7:43 ` Johannes Thumshirn
2020-02-12 7:17 ` [PATCH v7 5/8] btrfs: use BIOs instead of buffer_heads from superblock writeout Johannes Thumshirn
2020-02-12 7:30 ` Christoph Hellwig
2020-02-12 7:17 ` [PATCH v7 6/8] btrfs: remove btrfsic_submit_bh() Johannes Thumshirn
2020-02-12 7:17 ` [PATCH v7 7/8] btrfs: remove buffer_heads from btrfsic_process_written_block() Johannes Thumshirn
2020-02-12 7:17 ` [PATCH v7 8/8] btrfs: remove buffer_heads form superblock mirror integrity checking Johannes Thumshirn
2020-02-12 17:06 ` David Sterba
2020-02-13 9:12 ` Johannes Thumshirn
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