From patchwork Wed Feb 12 07:17:00 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Johannes Thumshirn X-Patchwork-Id: 11377655 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 02644921 for ; Wed, 12 Feb 2020 07:17:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id AF41520848 for ; Wed, 12 Feb 2020 07:17:13 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=wdc.com header.i=@wdc.com header.b="BbzInLxV" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728352AbgBLHRM (ORCPT ); Wed, 12 Feb 2020 02:17:12 -0500 Received: from esa2.hgst.iphmx.com ([68.232.143.124]:46465 "EHLO esa2.hgst.iphmx.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728341AbgBLHRM (ORCPT ); Wed, 12 Feb 2020 02:17:12 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=wdc.com; i=@wdc.com; q=dns/txt; s=dkim.wdc.com; t=1581491845; x=1613027845; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=H7SLEx5pAKOZvek04ltV7Q0qfzC6mC/2kvIz5PFcQz8=; b=BbzInLxVMJS6H+wTU9AARfj/NWlDIPp/2vzLv9Lkjyu6FAbhuo4GI1A3 Wk8tWJGhQ27Mxz+y+X8NWEqaHUmVZl/RJAFq65iBqGrBux+QFFPklQKRr dNDo57giN/30IOGgDs8eRw+PJYIJsGrrZAJQeyg+Nmgk6D3iLyrtrFw8C s4DUYHLuo6EtNQlQNegzoFMfZ97bObmO9sO+LMZ3ulaH8hJnOKDGBYlqM Y30apkD+e4/6fuhNTWDsBoN519AO52/AL28rQ/rHHuWb86dSpCMvjv7So 6Ddhay8ZVMgPIU0njGwMhlUHTDo91sev/bSLEXQQI/kiuvZfC3Dlp5VP1 w==; IronPort-SDR: g/gPLrbHQqGNZD74VIjCm7HKxkJ2naAEhlgX8P/raXaeCJFarDpSD57r8cU3X6BVM/ULedWjMC Iq/S5v/k/qq8oDuxGJfGXZdFR+7LgGlQja4vNZ0HVdpZlo+f9FZi9TyrXd893CCe+whP7Wy7sx lLgYnQSiR69xGekI+Px0bcxmm/a3WVkwOSUV/0SloB5EW+RMFwChnMyzQFtLalZh1IgTEjNmfK gvDefFK2QecqS7NNyEsCfmrgowWoc0q8DVnT6PNcAf32Rh7xRjCBAfyEKMtSw3YKKInG9HIyna s9c= X-IronPort-AV: E=Sophos;i="5.70,428,1574092800"; d="scan'208";a="231448462" Received: from h199-255-45-14.hgst.com (HELO uls-op-cesaep01.wdc.com) ([199.255.45.14]) by ob1.hgst.iphmx.com with ESMTP; 12 Feb 2020 15:17:25 +0800 IronPort-SDR: 1n8nZ+0XyxUi3fVnaR5OHerZGUW0uO5qSNwGu9NKyXVnN3k4cFddOfGDPmyqp3/essmwPpBAfH EFj9BK6tCwZkB1JrGBxDr3CYrdHls12dN54DjTdpmzlhZ7bIE1601PVzxNRyOpGlHmdAUeOW9v RnJbMLz00Hno/VVstfKbUnCqAb09t3YjVlvhtN+HdldCICnhcAEPm3f0EF3fIl9G+X4sLoPPuv tBzo0NpzEFRSVgb2rFE2VOgrXAwTn2lD959REsnhsd+z9/qBrP+zm0U5/poCHvNjTD+D1Hdzga bPRAmVigXKqOqhe4hM2eL7kE Received: from uls-op-cesaip01.wdc.com ([10.248.3.36]) by uls-op-cesaep01.wdc.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 11 Feb 2020 23:10:01 -0800 IronPort-SDR: 6wtKSgEgXSMB0FEnX3bq7vXM/MBAJR/oK8Li4BXMxFUKd1tyIwT7eIOvy9Dnr/7yUwL9OFnSGD hIK0haJP9imM6FYzDoAwbdqLgh1K1w4iuSkyjiPJmR9jP/XuAYmyKuCHIHeHvYjTIq7mWA+Lho ChNqvfDUPvgfpAYaXcUweIShY3O4tPDdrO7/ddXZT824O5HGsTO2y/trWDjf+4qRteAoqijD7L /648M5hqJZkgqxO2nOu6x7wvv1K5rDQr5WUF2yYEPe2xvd5aiKL35/+9ImkBW7SZwOBXXV4YkP dvo= WDCIronportException: Internal Received: from unknown (HELO redsun60.ssa.fujisawa.hgst.com) ([10.149.66.36]) by uls-op-cesaip01.wdc.com with ESMTP; 11 Feb 2020 23:17:11 -0800 From: Johannes Thumshirn To: David Sterba Cc: "linux-btrfs @ vger . kernel . org" , Johannes Thumshirn Subject: [PATCH v7 4/8] btrfs: use the page-cache for super block reading Date: Wed, 12 Feb 2020 16:17:00 +0900 Message-Id: <20200212071704.17505-5-johannes.thumshirn@wdc.com> X-Mailer: git-send-email 2.24.1 In-Reply-To: <20200212071704.17505-1-johannes.thumshirn@wdc.com> References: <20200212071704.17505-1-johannes.thumshirn@wdc.com> MIME-Version: 1.0 Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org Super-block reading in BTRFS is done using buffer_heads. Buffer_heads have some drawbacks, like not being able to propagate errors from the lower layers. Directly use the page cache for reading the super-blocks from disk or invalidating an on-disk super-block. We have to use the page-cache so to avoid races between mkfs and udev. See also 6f60cbd3ae44 ("btrfs: access superblock via pagecache in scan_one_device"). Signed-off-by: Johannes Thumshirn --- Changes to v6: - Warn if we can't write out a page for a superblock (David) Changes to v5: - Removed kmap()/kunmap() calls (hch/David) Changes to v4: - Remove mapping_gfp_constraint() and GFP_NOFAIL (hch) Changes to v3: - Use read_cache_pages() and write_one_page() for IO (hch) - Changed subject (David) - Dropped Josef's R-b due to change Changes to v2: - open-code kunmap() + put_page() (David) - fix double kunmap() (David) - don't use bi_set_op_attrs() (David) Changes to v1: - move 'super_page' into for-loop in btrfs_scratch_superblocks() (Nikolay) - switch to using pagecahce instead of alloc_pages() (Nikolay, David) --- fs/btrfs/disk-io.c | 74 ++++++++++++++++++------------------------ fs/btrfs/disk-io.h | 6 ++-- fs/btrfs/volumes.c | 80 ++++++++++++++++++++++++++-------------------- fs/btrfs/volumes.h | 4 +-- 4 files changed, 80 insertions(+), 84 deletions(-) diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c index 018681ec159b..9f422edd6cce 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -2850,7 +2850,6 @@ int __cold open_ctree(struct super_block *sb, struct btrfs_fs_devices *fs_device u64 features; u16 csum_type; struct btrfs_key location; - struct buffer_head *bh; struct btrfs_super_block *disk_super; struct btrfs_fs_info *fs_info = btrfs_sb(sb); struct btrfs_root *tree_root; @@ -2891,9 +2890,9 @@ int __cold open_ctree(struct super_block *sb, struct btrfs_fs_devices *fs_device /* * Read super block and check the signature bytes only */ - bh = btrfs_read_dev_super(fs_devices->latest_bdev); - if (IS_ERR(bh)) { - err = PTR_ERR(bh); + disk_super = btrfs_read_dev_super(fs_devices->latest_bdev); + if (IS_ERR(disk_super)) { + err = PTR_ERR(disk_super); goto fail_alloc; } @@ -2901,18 +2900,19 @@ int __cold open_ctree(struct super_block *sb, struct btrfs_fs_devices *fs_device * Verify the type first, if that or the the checksum value are * corrupted, we'll find out */ - csum_type = btrfs_super_csum_type((struct btrfs_super_block *)bh->b_data); + csum_type = btrfs_super_csum_type(disk_super); if (!btrfs_supported_super_csum(csum_type)) { btrfs_err(fs_info, "unsupported checksum algorithm: %u", csum_type); err = -EINVAL; - brelse(bh); + btrfs_release_disk_super(disk_super); goto fail_alloc; } ret = btrfs_init_csum_hash(fs_info, csum_type); if (ret) { err = ret; + btrfs_release_disk_super(disk_super); goto fail_alloc; } @@ -2920,10 +2920,10 @@ int __cold open_ctree(struct super_block *sb, struct btrfs_fs_devices *fs_device * We want to check superblock checksum, the type is stored inside. * Pass the whole disk block of size BTRFS_SUPER_INFO_SIZE (4k). */ - if (btrfs_check_super_csum(fs_info, bh->b_data)) { + if (btrfs_check_super_csum(fs_info, (u8 *) disk_super)) { btrfs_err(fs_info, "superblock checksum mismatch"); err = -EINVAL; - brelse(bh); + btrfs_release_disk_super(disk_super); goto fail_alloc; } @@ -2932,8 +2932,8 @@ int __cold open_ctree(struct super_block *sb, struct btrfs_fs_devices *fs_device * following bytes up to INFO_SIZE, the checksum is calculated from * the whole block of INFO_SIZE */ - memcpy(fs_info->super_copy, bh->b_data, sizeof(*fs_info->super_copy)); - brelse(bh); + memcpy(fs_info->super_copy, disk_super, sizeof(*fs_info->super_copy)); + btrfs_release_disk_super(disk_super); disk_super = fs_info->super_copy; @@ -3419,45 +3419,38 @@ static void btrfs_end_buffer_write_sync(struct buffer_head *bh, int uptodate) put_bh(bh); } -int btrfs_read_dev_one_super(struct block_device *bdev, int copy_num, - struct buffer_head **bh_ret) +struct btrfs_super_block *btrfs_read_dev_one_super(struct block_device *bdev, + int copy_num) { - struct buffer_head *bh; struct btrfs_super_block *super; + struct page *page; u64 bytenr; + struct address_space *mapping = bdev->bd_inode->i_mapping; bytenr = btrfs_sb_offset(copy_num); if (bytenr + BTRFS_SUPER_INFO_SIZE >= i_size_read(bdev->bd_inode)) - return -EINVAL; + return ERR_PTR(-EINVAL); - bh = __bread(bdev, bytenr / BTRFS_BDEV_BLOCKSIZE, BTRFS_SUPER_INFO_SIZE); - /* - * If we fail to read from the underlying devices, as of now - * the best option we have is to mark it EIO. - */ - if (!bh) - return -EIO; + page = read_cache_page_gfp(mapping, bytenr >> PAGE_SHIFT, GFP_NOFS); + if (IS_ERR(page)) + return ERR_PTR(-ENOMEM); - super = (struct btrfs_super_block *)bh->b_data; + super = page_address(page); if (btrfs_super_bytenr(super) != bytenr || btrfs_super_magic(super) != BTRFS_MAGIC) { - brelse(bh); - return -EINVAL; + btrfs_release_disk_super(super); + return ERR_PTR(-EINVAL); } - *bh_ret = bh; - return 0; + return super; } -struct buffer_head *btrfs_read_dev_super(struct block_device *bdev) +struct btrfs_super_block *btrfs_read_dev_super(struct block_device *bdev) { - struct buffer_head *bh; - struct buffer_head *latest = NULL; - struct btrfs_super_block *super; + struct btrfs_super_block *super, *latest = NULL; int i; u64 transid = 0; - int ret = -EINVAL; /* we would like to check all the supers, but that would make * a btrfs mount succeed after a mkfs from a different FS. @@ -3465,25 +3458,20 @@ struct buffer_head *btrfs_read_dev_super(struct block_device *bdev) * later supers, using BTRFS_SUPER_MIRROR_MAX instead */ for (i = 0; i < 1; i++) { - ret = btrfs_read_dev_one_super(bdev, i, &bh); - if (ret) + super = btrfs_read_dev_one_super(bdev, i); + if (IS_ERR(super)) continue; - super = (struct btrfs_super_block *)bh->b_data; - if (!latest || btrfs_super_generation(super) > transid) { - brelse(latest); - latest = bh; + if (latest) + btrfs_release_disk_super(super); + + latest = super; transid = btrfs_super_generation(super); - } else { - brelse(bh); } } - if (!latest) - return ERR_PTR(ret); - - return latest; + return super; } /* diff --git a/fs/btrfs/disk-io.h b/fs/btrfs/disk-io.h index db21ab614357..59c885860bf8 100644 --- a/fs/btrfs/disk-io.h +++ b/fs/btrfs/disk-io.h @@ -56,9 +56,9 @@ int __cold open_ctree(struct super_block *sb, char *options); void __cold close_ctree(struct btrfs_fs_info *fs_info); int write_all_supers(struct btrfs_fs_info *fs_info, int max_mirrors); -struct buffer_head *btrfs_read_dev_super(struct block_device *bdev); -int btrfs_read_dev_one_super(struct block_device *bdev, int copy_num, - struct buffer_head **bh_ret); +struct btrfs_super_block *btrfs_read_dev_super(struct block_device *bdev); +struct btrfs_super_block *btrfs_read_dev_one_super(struct block_device *bdev, + int copy_num); int btrfs_commit_super(struct btrfs_fs_info *fs_info); struct btrfs_root *btrfs_read_tree_root(struct btrfs_root *tree_root, struct btrfs_key *key); diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c index e17d4d7a6eb4..daf9c10db337 100644 --- a/fs/btrfs/volumes.c +++ b/fs/btrfs/volumes.c @@ -6,7 +6,6 @@ #include #include #include -#include #include #include #include @@ -32,7 +31,8 @@ #include "block-group.h" #include "discard.h" -static void btrfs_scratch_superblocks(struct block_device *bdev, +static void btrfs_scratch_superblocks(struct btrfs_fs_info *fs_info, + struct block_device *bdev, const char *device_path); const struct btrfs_raid_attr btrfs_raid_array[BTRFS_NR_RAID_TYPES] = { @@ -503,7 +503,7 @@ static struct btrfs_fs_devices *find_fsid_with_metadata_uuid( static int btrfs_get_bdev_and_sb(const char *device_path, fmode_t flags, void *holder, int flush, struct block_device **bdev, - struct buffer_head **bh) + struct btrfs_super_block **disk_super) { int ret; @@ -522,9 +522,9 @@ btrfs_get_bdev_and_sb(const char *device_path, fmode_t flags, void *holder, goto error; } invalidate_bdev(*bdev); - *bh = btrfs_read_dev_super(*bdev); - if (IS_ERR(*bh)) { - ret = PTR_ERR(*bh); + *disk_super = btrfs_read_dev_super(*bdev); + if (IS_ERR(*disk_super)) { + ret = PTR_ERR(*disk_super); blkdev_put(*bdev, flags); goto error; } @@ -533,7 +533,6 @@ btrfs_get_bdev_and_sb(const char *device_path, fmode_t flags, void *holder, error: *bdev = NULL; - *bh = NULL; return ret; } @@ -614,7 +613,6 @@ static int btrfs_open_one_device(struct btrfs_fs_devices *fs_devices, { struct request_queue *q; struct block_device *bdev; - struct buffer_head *bh; struct btrfs_super_block *disk_super; u64 devid; int ret; @@ -625,17 +623,16 @@ static int btrfs_open_one_device(struct btrfs_fs_devices *fs_devices, return -EINVAL; ret = btrfs_get_bdev_and_sb(device->name->str, flags, holder, 1, - &bdev, &bh); + &bdev, &disk_super); if (ret) return ret; - disk_super = (struct btrfs_super_block *)bh->b_data; devid = btrfs_stack_device_id(&disk_super->dev_item); if (devid != device->devid) - goto error_brelse; + goto error_free_page; if (memcmp(device->uuid, disk_super->dev_item.uuid, BTRFS_UUID_SIZE)) - goto error_brelse; + goto error_free_page; device->generation = btrfs_super_generation(disk_super); @@ -644,7 +641,7 @@ static int btrfs_open_one_device(struct btrfs_fs_devices *fs_devices, BTRFS_FEATURE_INCOMPAT_METADATA_UUID) { pr_err( "BTRFS: Invalid seeding and uuid-changed device detected\n"); - goto error_brelse; + goto error_free_page; } clear_bit(BTRFS_DEV_STATE_WRITEABLE, &device->dev_state); @@ -670,12 +667,12 @@ static int btrfs_open_one_device(struct btrfs_fs_devices *fs_devices, fs_devices->rw_devices++; list_add_tail(&device->dev_alloc_list, &fs_devices->alloc_list); } - brelse(bh); + btrfs_release_disk_super(disk_super); return 0; -error_brelse: - brelse(bh); +error_free_page: + btrfs_release_disk_super(disk_super); blkdev_put(bdev, flags); return -EINVAL; @@ -1250,8 +1247,10 @@ int btrfs_open_devices(struct btrfs_fs_devices *fs_devices, return ret; } -void btrfs_release_disk_super(struct page *page) +void btrfs_release_disk_super(struct btrfs_super_block *super) { + struct page *page = virt_to_page(super); + put_page(page); } @@ -1289,7 +1288,7 @@ static int btrfs_read_disk_super(struct block_device *bdev, u64 bytenr, if (btrfs_super_bytenr(*disk_super) != bytenr || btrfs_super_magic(*disk_super) != BTRFS_MAGIC) { - btrfs_release_disk_super(*page); + btrfs_release_disk_super(p); return 1; } @@ -1352,7 +1351,7 @@ struct btrfs_device *btrfs_scan_one_device(const char *path, fmode_t flags, btrfs_free_stale_devices(path, device); } - btrfs_release_disk_super(page); + btrfs_release_disk_super(disk_super); error_bdev_put: blkdev_put(bdev, flags); @@ -2069,7 +2068,8 @@ int btrfs_rm_device(struct btrfs_fs_info *fs_info, const char *device_path, * supers and free the device. */ if (test_bit(BTRFS_DEV_STATE_WRITEABLE, &device->dev_state)) - btrfs_scratch_superblocks(device->bdev, device->name->str); + btrfs_scratch_superblocks(fs_info, device->bdev, + device->name->str); btrfs_close_bdev(device); synchronize_rcu(); @@ -2137,7 +2137,8 @@ void btrfs_rm_dev_replace_free_srcdev(struct btrfs_device *srcdev) if (test_bit(BTRFS_DEV_STATE_WRITEABLE, &srcdev->dev_state)) { /* zero out the old super if it is writable */ - btrfs_scratch_superblocks(srcdev->bdev, srcdev->name->str); + btrfs_scratch_superblocks(fs_info, srcdev->bdev, + srcdev->name->str); } btrfs_close_bdev(srcdev); @@ -2196,7 +2197,8 @@ void btrfs_destroy_dev_replace_tgtdev(struct btrfs_device *tgtdev) * is already out of device list, so we don't have to hold * the device_list_mutex lock. */ - btrfs_scratch_superblocks(tgtdev->bdev, tgtdev->name->str); + btrfs_scratch_superblocks(tgtdev->fs_info, tgtdev->bdev, + tgtdev->name->str); btrfs_close_bdev(tgtdev); synchronize_rcu(); @@ -2211,14 +2213,14 @@ static struct btrfs_device *btrfs_find_device_by_path( u64 devid; u8 *dev_uuid; struct block_device *bdev; - struct buffer_head *bh; struct btrfs_device *device; ret = btrfs_get_bdev_and_sb(device_path, FMODE_READ, - fs_info->bdev_holder, 0, &bdev, &bh); + fs_info->bdev_holder, 0, &bdev, + &disk_super); if (ret) return ERR_PTR(ret); - disk_super = (struct btrfs_super_block *)bh->b_data; + devid = btrfs_stack_device_id(&disk_super->dev_item); dev_uuid = disk_super->dev_item.uuid; if (btrfs_fs_incompat(fs_info, METADATA_UUID)) @@ -2228,7 +2230,7 @@ static struct btrfs_device *btrfs_find_device_by_path( device = btrfs_find_device(fs_info->fs_devices, devid, dev_uuid, disk_super->fsid, true); - brelse(bh); + btrfs_release_disk_super(disk_super); if (!device) device = ERR_PTR(-ENOENT); blkdev_put(bdev, FMODE_READ); @@ -7319,10 +7321,10 @@ int btrfs_get_dev_stats(struct btrfs_fs_info *fs_info, return 0; } -static void btrfs_scratch_superblocks(struct block_device *bdev, - const char *device_path) +static void btrfs_scratch_superblocks(struct btrfs_fs_info *fs_info, + struct block_device *bdev, + const char *device_path) { - struct buffer_head *bh; struct btrfs_super_block *disk_super; int copy_num; @@ -7331,16 +7333,24 @@ static void btrfs_scratch_superblocks(struct block_device *bdev, for (copy_num = 0; copy_num < BTRFS_SUPER_MIRROR_MAX; copy_num++) { + struct page *page; + int err; - if (btrfs_read_dev_one_super(bdev, copy_num, &bh)) + disk_super = btrfs_read_dev_one_super(bdev, copy_num); + if (IS_ERR(disk_super)) continue; - disk_super = (struct btrfs_super_block *)bh->b_data; - memset(&disk_super->magic, 0, sizeof(disk_super->magic)); - set_buffer_dirty(bh); - sync_dirty_buffer(bh); - brelse(bh); + + page = virt_to_page(disk_super); + set_page_dirty(page); + lock_page(page); /* write_on_page() unlocks the page */ + err = write_one_page(page); + if (err) + btrfs_warn(fs_info, "error clearing superblock number %d (%d)", + copy_num, err); + btrfs_release_disk_super(disk_super); + } /* Notify udev that device has changed */ diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h index a3d86ee6a883..3f52c3a05af8 100644 --- a/fs/btrfs/volumes.h +++ b/fs/btrfs/volumes.h @@ -17,8 +17,6 @@ extern struct mutex uuid_mutex; #define BTRFS_STRIPE_LEN SZ_64K -struct buffer_head; - struct btrfs_io_geometry { /* remaining bytes before crossing a stripe */ u64 len; @@ -482,7 +480,7 @@ int btrfs_finish_chunk_alloc(struct btrfs_trans_handle *trans, int btrfs_remove_chunk(struct btrfs_trans_handle *trans, u64 chunk_offset); struct extent_map *btrfs_get_chunk_map(struct btrfs_fs_info *fs_info, u64 logical, u64 length); -void btrfs_release_disk_super(struct page *page); +void btrfs_release_disk_super(struct btrfs_super_block *super); static inline void btrfs_dev_stat_inc(struct btrfs_device *dev, int index)