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Message-ID: <924994ed-64c8-ca11-75c1-cb1a1f0f6d94@sandeen.net>
Date: Fri, 25 May 2018 17:32:25 -0500
From: Eric Sandeen <sandeen@...deen.net>
To: Ross Zwisler <ross.zwisler@...ux.intel.com>,
Toshi Kani <toshi.kani@....com>,
Mike Snitzer <snitzer@...hat.com>, dm-devel@...hat.com
Cc: linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-nvdimm@...ts.01.org, linux-xfs@...r.kernel.org,
"Darrick J. Wong" <darrick.wong@...cle.com>
Subject: Re: [PATCH resend 1/7] fs: allow per-device dax status checking for
filesystems
On 5/25/18 5:00 PM, Ross Zwisler wrote:
> From: "Darrick J. Wong" <darrick.wong@...cle.com>
>
> Remove __bdev_dax_supported and change to bdev_dax_supported that takes a
> bdev parameter. This enables multi-device filesystems like xfs to check
> that a dax device can work for the particular filesystem. Once that's
> in place, actually fix all the parts of XFS where we need to be able to
> distinguish between datadev and rtdev.
>
> This patch fixes the problem where we screw up the dax support checking
> in xfs if the datadev and rtdev have different dax capabilities.
I wonder where we might be able to document this wrinkle, i.e. mount -o dax
means at least /one/ of the devices must support it, and then at runtime
whichever file you try to use dax on still needs to be on a device that
supports it ... but ok, anyway this seems fine functionally.
you've assured me that xfstests are coming ;)
Reviewed-by: Eric Sandeen <sandeen@...hat.com>
> Signed-off-by: Darrick J. Wong <darrick.wong@...cle.com>
> Signed-off-by: Ross Zwisler <ross.zwisler@...ux.intel.com>
> ---
> drivers/dax/super.c | 30 +++++++++++++++---------------
> fs/ext2/super.c | 2 +-
> fs/ext4/super.c | 2 +-
> fs/xfs/xfs_ioctl.c | 3 ++-
> fs/xfs/xfs_iops.c | 30 +++++++++++++++++++++++++-----
> fs/xfs/xfs_super.c | 10 ++++++++--
> include/linux/dax.h | 10 +++-------
> 7 files changed, 55 insertions(+), 32 deletions(-)
>
> diff --git a/drivers/dax/super.c b/drivers/dax/super.c
> index 2b2332b605e4..9206539c8330 100644
> --- a/drivers/dax/super.c
> +++ b/drivers/dax/super.c
> @@ -73,8 +73,8 @@ EXPORT_SYMBOL_GPL(fs_dax_get_by_bdev);
> #endif
>
> /**
> - * __bdev_dax_supported() - Check if the device supports dax for filesystem
> - * @sb: The superblock of the device
> + * bdev_dax_supported() - Check if the device supports dax for filesystem
> + * @bdev: block device to check
> * @blocksize: The block size of the device
> *
> * This is a library function for filesystems to check if the block device
> @@ -82,33 +82,33 @@ EXPORT_SYMBOL_GPL(fs_dax_get_by_bdev);
> *
> * Return: negative errno if unsupported, 0 if supported.
> */
> -int __bdev_dax_supported(struct super_block *sb, int blocksize)
> +int bdev_dax_supported(struct block_device *bdev, int blocksize)
> {
> - struct block_device *bdev = sb->s_bdev;
> struct dax_device *dax_dev;
> pgoff_t pgoff;
> int err, id;
> void *kaddr;
> pfn_t pfn;
> long len;
> + char buf[BDEVNAME_SIZE];
>
> if (blocksize != PAGE_SIZE) {
> - pr_debug("VFS (%s): error: unsupported blocksize for dax\n",
> - sb->s_id);
> + pr_debug("%s: error: unsupported blocksize for dax\n",
> + bdevname(bdev, buf));
> return -EINVAL;
> }
>
> err = bdev_dax_pgoff(bdev, 0, PAGE_SIZE, &pgoff);
> if (err) {
> - pr_debug("VFS (%s): error: unaligned partition for dax\n",
> - sb->s_id);
> + pr_debug("%s: error: unaligned partition for dax\n",
> + bdevname(bdev, buf));
> return err;
> }
>
> dax_dev = dax_get_by_host(bdev->bd_disk->disk_name);
> if (!dax_dev) {
> - pr_debug("VFS (%s): error: device does not support dax\n",
> - sb->s_id);
> + pr_debug("%s: error: device does not support dax\n",
> + bdevname(bdev, buf));
> return -EOPNOTSUPP;
> }
>
> @@ -119,8 +119,8 @@ int __bdev_dax_supported(struct super_block *sb, int blocksize)
> put_dax(dax_dev);
>
> if (len < 1) {
> - pr_debug("VFS (%s): error: dax access failed (%ld)\n",
> - sb->s_id, len);
> + pr_debug("%s: error: dax access failed (%ld)\n",
> + bdevname(bdev, buf), len);
> return len < 0 ? len : -EIO;
> }
>
> @@ -137,14 +137,14 @@ int __bdev_dax_supported(struct super_block *sb, int blocksize)
> } else if (pfn_t_devmap(pfn)) {
> /* pass */;
> } else {
> - pr_debug("VFS (%s): error: dax support not enabled\n",
> - sb->s_id);
> + pr_debug("%s: error: dax support not enabled\n",
> + bdevname(bdev, buf));
> return -EOPNOTSUPP;
> }
>
> return 0;
> }
> -EXPORT_SYMBOL_GPL(__bdev_dax_supported);
> +EXPORT_SYMBOL_GPL(bdev_dax_supported);
> #endif
>
> enum dax_device_flags {
> diff --git a/fs/ext2/super.c b/fs/ext2/super.c
> index de1694512f1f..9627c3054b5c 100644
> --- a/fs/ext2/super.c
> +++ b/fs/ext2/super.c
> @@ -961,7 +961,7 @@ static int ext2_fill_super(struct super_block *sb, void *data, int silent)
> blocksize = BLOCK_SIZE << le32_to_cpu(sbi->s_es->s_log_block_size);
>
> if (sbi->s_mount_opt & EXT2_MOUNT_DAX) {
> - err = bdev_dax_supported(sb, blocksize);
> + err = bdev_dax_supported(sb->s_bdev, blocksize);
> if (err) {
> ext2_msg(sb, KERN_ERR,
> "DAX unsupported by block device. Turning off DAX.");
> diff --git a/fs/ext4/super.c b/fs/ext4/super.c
> index eb104e8476f0..089170e99895 100644
> --- a/fs/ext4/super.c
> +++ b/fs/ext4/super.c
> @@ -3732,7 +3732,7 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
> " that may contain inline data");
> sbi->s_mount_opt &= ~EXT4_MOUNT_DAX;
> }
> - err = bdev_dax_supported(sb, blocksize);
> + err = bdev_dax_supported(sb->s_bdev, blocksize);
> if (err) {
> ext4_msg(sb, KERN_ERR,
> "DAX unsupported by block device. Turning off DAX.");
> diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c
> index 89fb1eb80aae..0effd46b965f 100644
> --- a/fs/xfs/xfs_ioctl.c
> +++ b/fs/xfs/xfs_ioctl.c
> @@ -1103,7 +1103,8 @@ xfs_ioctl_setattr_dax_invalidate(
> if (fa->fsx_xflags & FS_XFLAG_DAX) {
> if (!(S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode)))
> return -EINVAL;
> - if (bdev_dax_supported(sb, sb->s_blocksize) < 0)
> + if (bdev_dax_supported(xfs_find_bdev_for_inode(VFS_I(ip)),
> + sb->s_blocksize) < 0)
> return -EINVAL;
> }
>
> diff --git a/fs/xfs/xfs_iops.c b/fs/xfs/xfs_iops.c
> index a3ed3c811dfa..6e83acf74a95 100644
> --- a/fs/xfs/xfs_iops.c
> +++ b/fs/xfs/xfs_iops.c
> @@ -1195,6 +1195,30 @@ static const struct inode_operations xfs_inline_symlink_inode_operations = {
> .update_time = xfs_vn_update_time,
> };
>
> +/* Figure out if this file actually supports DAX. */
> +static bool
> +xfs_inode_supports_dax(
> + struct xfs_inode *ip)
> +{
> + struct xfs_mount *mp = ip->i_mount;
> +
> + /* Only supported on non-reflinked files. */
> + if (!S_ISREG(VFS_I(ip)->i_mode) || xfs_is_reflink_inode(ip))
> + return false;
> +
> + /* DAX mount option or DAX iflag must be set. */
> + if (!(mp->m_flags & XFS_MOUNT_DAX) &&
> + !(ip->i_d.di_flags2 & XFS_DIFLAG2_DAX))
> + return false;
> +
> + /* Block size must match page size */
> + if (mp->m_sb.sb_blocksize != PAGE_SIZE)
> + return false;
> +
> + /* Device has to support DAX too. */
> + return xfs_find_daxdev_for_inode(VFS_I(ip)) != NULL;
> +}
> +
> STATIC void
> xfs_diflags_to_iflags(
> struct inode *inode,
> @@ -1213,11 +1237,7 @@ xfs_diflags_to_iflags(
> inode->i_flags |= S_SYNC;
> if (flags & XFS_DIFLAG_NOATIME)
> inode->i_flags |= S_NOATIME;
> - if (S_ISREG(inode->i_mode) &&
> - ip->i_mount->m_sb.sb_blocksize == PAGE_SIZE &&
> - !xfs_is_reflink_inode(ip) &&
> - (ip->i_mount->m_flags & XFS_MOUNT_DAX ||
> - ip->i_d.di_flags2 & XFS_DIFLAG2_DAX))
> + if (xfs_inode_supports_dax(ip))
> inode->i_flags |= S_DAX;
> }
>
> diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c
> index d71424052917..62188c2a4c36 100644
> --- a/fs/xfs/xfs_super.c
> +++ b/fs/xfs/xfs_super.c
> @@ -1690,11 +1690,17 @@ xfs_fs_fill_super(
> sb->s_flags |= SB_I_VERSION;
>
> if (mp->m_flags & XFS_MOUNT_DAX) {
> + int error2 = 0;
> +
> xfs_warn(mp,
> "DAX enabled. Warning: EXPERIMENTAL, use at your own risk");
>
> - error = bdev_dax_supported(sb, sb->s_blocksize);
> - if (error) {
> + error = bdev_dax_supported(mp->m_ddev_targp->bt_bdev,
> + sb->s_blocksize);
> + if (mp->m_rtdev_targp)
> + error2 = bdev_dax_supported(mp->m_rtdev_targp->bt_bdev,
> + sb->s_blocksize);
> + if (error && error2) {
> xfs_alert(mp,
> "DAX unsupported by block device. Turning off DAX.");
> mp->m_flags &= ~XFS_MOUNT_DAX;
> diff --git a/include/linux/dax.h b/include/linux/dax.h
> index f9eb22ad341e..509a85ac8470 100644
> --- a/include/linux/dax.h
> +++ b/include/linux/dax.h
> @@ -64,12 +64,7 @@ static inline bool dax_write_cache_enabled(struct dax_device *dax_dev)
> struct writeback_control;
> int bdev_dax_pgoff(struct block_device *, sector_t, size_t, pgoff_t *pgoff);
> #if IS_ENABLED(CONFIG_FS_DAX)
> -int __bdev_dax_supported(struct super_block *sb, int blocksize);
> -static inline int bdev_dax_supported(struct super_block *sb, int blocksize)
> -{
> - return __bdev_dax_supported(sb, blocksize);
> -}
> -
> +int bdev_dax_supported(struct block_device *bdev, int blocksize);
> static inline struct dax_device *fs_dax_get_by_host(const char *host)
> {
> return dax_get_by_host(host);
> @@ -84,7 +79,8 @@ struct dax_device *fs_dax_get_by_bdev(struct block_device *bdev);
> int dax_writeback_mapping_range(struct address_space *mapping,
> struct block_device *bdev, struct writeback_control *wbc);
> #else
> -static inline int bdev_dax_supported(struct super_block *sb, int blocksize)
> +static inline int bdev_dax_supported(struct block_device *bdev,
> + int blocksize)
> {
> return -EOPNOTSUPP;
> }
>
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