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Message-ID: <20170828162827.GA4757@magnolia>
Date: Mon, 28 Aug 2017 09:28:27 -0700
From: "Darrick J. Wong" <darrick.wong@...cle.com>
To: Dan Williams <dan.j.williams@...el.com>
Cc: linux-fsdevel@...r.kernel.org, jack@...e.cz,
linux-nvdimm@...ts.01.org, linux-xfs@...r.kernel.org,
linux-ext4@...r.kernel.org, hch@....de
Subject: Re: [PATCH v2 1/2] fs, xfs: perform dax_device lookup at mount
On Sun, Aug 27, 2017 at 08:48:40PM -0700, Dan Williams wrote:
> The ->iomap_begin() operation is a hot path, so cache the
> fs_dax_get_by_host() result at mount time to avoid the incurring the
> hash lookup overhead on a per-i/o basis.
>
> Cc: "Darrick J. Wong" <darrick.wong@...cle.com>
> Reported-by: Christoph Hellwig <hch@....de>
> Signed-off-by: Dan Williams <dan.j.williams@...el.com>
Looks good,
Reviewed-by: Darrick J. Wong <darrick.wong@...cle.com>
> ---
> drivers/dax/super.c | 10 ++++++++++
> fs/super.c | 26 +++++++++++++++++++++++---
> fs/xfs/xfs_aops.c | 13 +++++++++++++
> fs/xfs/xfs_aops.h | 1 +
> fs/xfs/xfs_buf.c | 4 +++-
> fs/xfs/xfs_buf.h | 3 ++-
> fs/xfs/xfs_iomap.c | 10 +---------
> fs/xfs/xfs_super.c | 21 +++++++++++++++++----
> include/linux/dax.h | 6 ++++++
> include/linux/fs.h | 1 +
> 10 files changed, 77 insertions(+), 18 deletions(-)
>
> diff --git a/drivers/dax/super.c b/drivers/dax/super.c
> index 938eb4868f7f..b699aac268a6 100644
> --- a/drivers/dax/super.c
> +++ b/drivers/dax/super.c
> @@ -46,6 +46,8 @@ void dax_read_unlock(int id)
> EXPORT_SYMBOL_GPL(dax_read_unlock);
>
> #ifdef CONFIG_BLOCK
> +#include <linux/blkdev.h>
> +
> int bdev_dax_pgoff(struct block_device *bdev, sector_t sector, size_t size,
> pgoff_t *pgoff)
> {
> @@ -59,6 +61,14 @@ int bdev_dax_pgoff(struct block_device *bdev, sector_t sector, size_t size,
> }
> EXPORT_SYMBOL(bdev_dax_pgoff);
>
> +struct dax_device *fs_dax_get_by_bdev(struct block_device *bdev)
> +{
> + if (!blk_queue_dax(bdev->bd_queue))
> + return NULL;
> + return fs_dax_get_by_host(bdev->bd_disk->disk_name);
> +}
> +EXPORT_SYMBOL_GPL(fs_dax_get_by_bdev);
> +
> /**
> * __bdev_dax_supported() - Check if the device supports dax for filesystem
> * @sb: The superblock of the device
> diff --git a/fs/super.c b/fs/super.c
> index 6bc3352adcf3..671889b02bed 100644
> --- a/fs/super.c
> +++ b/fs/super.c
> @@ -23,6 +23,7 @@
> #include <linux/export.h>
> #include <linux/slab.h>
> #include <linux/blkdev.h>
> +#include <linux/dax.h>
> #include <linux/mount.h>
> #include <linux/security.h>
> #include <linux/writeback.h> /* for the emergency remount stuff */
> @@ -1048,9 +1049,17 @@ struct dentry *mount_ns(struct file_system_type *fs_type,
> EXPORT_SYMBOL(mount_ns);
>
> #ifdef CONFIG_BLOCK
> +struct sget_devs {
> + struct block_device *bdev;
> + struct dax_device *dax_dev;
> +};
> +
> static int set_bdev_super(struct super_block *s, void *data)
> {
> - s->s_bdev = data;
> + struct sget_devs *devs = data;
> +
> + s->s_bdev = devs->bdev;
> + s->s_daxdev = devs->dax_dev;
> s->s_dev = s->s_bdev->bd_dev;
> s->s_bdi = bdi_get(s->s_bdev->bd_bdi);
>
> @@ -1059,14 +1068,18 @@ static int set_bdev_super(struct super_block *s, void *data)
>
> static int test_bdev_super(struct super_block *s, void *data)
> {
> - return (void *)s->s_bdev == data;
> + struct sget_devs *devs = data;
> +
> + return s->s_bdev == devs->bdev;
> }
>
> struct dentry *mount_bdev(struct file_system_type *fs_type,
> int flags, const char *dev_name, void *data,
> int (*fill_super)(struct super_block *, void *, int))
> {
> + struct sget_devs devs;
> struct block_device *bdev;
> + struct dax_device *dax_dev;
> struct super_block *s;
> fmode_t mode = FMODE_READ | FMODE_EXCL;
> int error = 0;
> @@ -1077,6 +1090,7 @@ struct dentry *mount_bdev(struct file_system_type *fs_type,
> bdev = blkdev_get_by_path(dev_name, mode, fs_type);
> if (IS_ERR(bdev))
> return ERR_CAST(bdev);
> + dax_dev = fs_dax_get_by_bdev(bdev);
>
> /*
> * once the super is inserted into the list by sget, s_umount
> @@ -1089,8 +1103,10 @@ struct dentry *mount_bdev(struct file_system_type *fs_type,
> error = -EBUSY;
> goto error_bdev;
> }
> + devs.bdev = bdev;
> + devs.dax_dev = dax_dev;
> s = sget(fs_type, test_bdev_super, set_bdev_super, flags | MS_NOSEC,
> - bdev);
> + &devs);
> mutex_unlock(&bdev->bd_fsfreeze_mutex);
> if (IS_ERR(s))
> goto error_s;
> @@ -1111,6 +1127,7 @@ struct dentry *mount_bdev(struct file_system_type *fs_type,
> */
> up_write(&s->s_umount);
> blkdev_put(bdev, mode);
> + fs_put_dax(dax_dev);
> down_write(&s->s_umount);
> } else {
> s->s_mode = mode;
> @@ -1132,6 +1149,7 @@ struct dentry *mount_bdev(struct file_system_type *fs_type,
> error = PTR_ERR(s);
> error_bdev:
> blkdev_put(bdev, mode);
> + fs_put_dax(dax_dev);
> error:
> return ERR_PTR(error);
> }
> @@ -1140,6 +1158,7 @@ EXPORT_SYMBOL(mount_bdev);
> void kill_block_super(struct super_block *sb)
> {
> struct block_device *bdev = sb->s_bdev;
> + struct dax_device *dax_dev = sb->s_daxdev;
> fmode_t mode = sb->s_mode;
>
> bdev->bd_super = NULL;
> @@ -1147,6 +1166,7 @@ void kill_block_super(struct super_block *sb)
> sync_blockdev(bdev);
> WARN_ON_ONCE(!(mode & FMODE_EXCL));
> blkdev_put(bdev, mode | FMODE_EXCL);
> + fs_put_dax(dax_dev);
> }
>
> EXPORT_SYMBOL(kill_block_super);
> diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c
> index 6bf120bb1a17..78185f3b10b2 100644
> --- a/fs/xfs/xfs_aops.c
> +++ b/fs/xfs/xfs_aops.c
> @@ -80,6 +80,19 @@ xfs_find_bdev_for_inode(
> return mp->m_ddev_targp->bt_bdev;
> }
>
> +struct dax_device *
> +xfs_find_daxdev_for_inode(
> + struct inode *inode)
> +{
> + struct xfs_inode *ip = XFS_I(inode);
> + struct xfs_mount *mp = ip->i_mount;
> +
> + if (XFS_IS_REALTIME_INODE(ip))
> + return mp->m_rtdev_targp->bt_daxdev;
> + else
> + return mp->m_ddev_targp->bt_daxdev;
> +}
> +
> /*
> * We're now finished for good with this page. Update the page state via the
> * associated buffer_heads, paying attention to the start and end offsets that
> diff --git a/fs/xfs/xfs_aops.h b/fs/xfs/xfs_aops.h
> index cc174ec6c2fd..88c85ea63da0 100644
> --- a/fs/xfs/xfs_aops.h
> +++ b/fs/xfs/xfs_aops.h
> @@ -59,5 +59,6 @@ int xfs_setfilesize(struct xfs_inode *ip, xfs_off_t offset, size_t size);
>
> extern void xfs_count_page_state(struct page *, int *, int *);
> extern struct block_device *xfs_find_bdev_for_inode(struct inode *);
> +extern struct dax_device *xfs_find_daxdev_for_inode(struct inode *);
>
> #endif /* __XFS_AOPS_H__ */
> diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c
> index 72f038492ba8..6deb86c845d1 100644
> --- a/fs/xfs/xfs_buf.c
> +++ b/fs/xfs/xfs_buf.c
> @@ -1802,7 +1802,8 @@ xfs_setsize_buftarg_early(
> xfs_buftarg_t *
> xfs_alloc_buftarg(
> struct xfs_mount *mp,
> - struct block_device *bdev)
> + struct block_device *bdev,
> + struct dax_device *dax_dev)
> {
> xfs_buftarg_t *btp;
>
> @@ -1811,6 +1812,7 @@ xfs_alloc_buftarg(
> btp->bt_mount = mp;
> btp->bt_dev = bdev->bd_dev;
> btp->bt_bdev = bdev;
> + btp->bt_daxdev = dax_dev;
>
> if (xfs_setsize_buftarg_early(btp, bdev))
> goto error;
> diff --git a/fs/xfs/xfs_buf.h b/fs/xfs/xfs_buf.h
> index 20721261dae5..bf71507ddb16 100644
> --- a/fs/xfs/xfs_buf.h
> +++ b/fs/xfs/xfs_buf.h
> @@ -108,6 +108,7 @@ typedef unsigned int xfs_buf_flags_t;
> typedef struct xfs_buftarg {
> dev_t bt_dev;
> struct block_device *bt_bdev;
> + struct dax_device *bt_daxdev;
> struct xfs_mount *bt_mount;
> unsigned int bt_meta_sectorsize;
> size_t bt_meta_sectormask;
> @@ -385,7 +386,7 @@ xfs_buf_update_cksum(struct xfs_buf *bp, unsigned long cksum_offset)
> * Handling of buftargs.
> */
> extern xfs_buftarg_t *xfs_alloc_buftarg(struct xfs_mount *,
> - struct block_device *);
> + struct block_device *, struct dax_device *);
> extern void xfs_free_buftarg(struct xfs_mount *, struct xfs_buftarg *);
> extern void xfs_wait_buftarg(xfs_buftarg_t *);
> extern int xfs_setsize_buftarg(xfs_buftarg_t *, unsigned int);
> diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c
> index 813394c62849..7c934e407332 100644
> --- a/fs/xfs/xfs_iomap.c
> +++ b/fs/xfs/xfs_iomap.c
> @@ -69,6 +69,7 @@ xfs_bmbt_to_iomap(
> iomap->offset = XFS_FSB_TO_B(mp, imap->br_startoff);
> iomap->length = XFS_FSB_TO_B(mp, imap->br_blockcount);
> iomap->bdev = xfs_find_bdev_for_inode(VFS_I(ip));
> + iomap->dax_dev = xfs_find_daxdev_for_inode(VFS_I(ip));
> }
>
> xfs_extlen_t
> @@ -976,7 +977,6 @@ xfs_file_iomap_begin(
> int nimaps = 1, error = 0;
> bool shared = false, trimmed = false;
> unsigned lockmode;
> - struct block_device *bdev;
>
> if (XFS_FORCED_SHUTDOWN(mp))
> return -EIO;
> @@ -1087,13 +1087,6 @@ xfs_file_iomap_begin(
>
> xfs_bmbt_to_iomap(ip, iomap, &imap);
>
> - /* optionally associate a dax device with the iomap bdev */
> - bdev = iomap->bdev;
> - if (blk_queue_dax(bdev->bd_queue))
> - iomap->dax_dev = fs_dax_get_by_host(bdev->bd_disk->disk_name);
> - else
> - iomap->dax_dev = NULL;
> -
> if (shared)
> iomap->flags |= IOMAP_F_SHARED;
> return 0;
> @@ -1171,7 +1164,6 @@ xfs_file_iomap_end(
> unsigned flags,
> struct iomap *iomap)
> {
> - fs_put_dax(iomap->dax_dev);
> if ((flags & IOMAP_WRITE) && iomap->type == IOMAP_DELALLOC)
> return xfs_file_iomap_end_delalloc(XFS_I(inode), offset,
> length, written, iomap);
> diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c
> index 38aaacdbb8b3..d863f96b16e2 100644
> --- a/fs/xfs/xfs_super.c
> +++ b/fs/xfs/xfs_super.c
> @@ -716,13 +716,19 @@ xfs_close_devices(
> {
> if (mp->m_logdev_targp && mp->m_logdev_targp != mp->m_ddev_targp) {
> struct block_device *logdev = mp->m_logdev_targp->bt_bdev;
> + struct dax_device *dax_logdev = mp->m_logdev_targp->bt_daxdev;
> +
> xfs_free_buftarg(mp, mp->m_logdev_targp);
> xfs_blkdev_put(logdev);
> + fs_put_dax(dax_logdev);
> }
> if (mp->m_rtdev_targp) {
> struct block_device *rtdev = mp->m_rtdev_targp->bt_bdev;
> + struct dax_device *dax_rtdev = mp->m_rtdev_targp->bt_daxdev;
> +
> xfs_free_buftarg(mp, mp->m_rtdev_targp);
> xfs_blkdev_put(rtdev);
> + fs_put_dax(dax_rtdev);
> }
> xfs_free_buftarg(mp, mp->m_ddev_targp);
> }
> @@ -742,7 +748,9 @@ xfs_open_devices(
> struct xfs_mount *mp)
> {
> struct block_device *ddev = mp->m_super->s_bdev;
> + struct dax_device *dax_ddev = mp->m_super->s_daxdev;
> struct block_device *logdev = NULL, *rtdev = NULL;
> + struct dax_device *dax_logdev = NULL, *dax_rtdev = NULL;
> int error;
>
> /*
> @@ -752,6 +760,7 @@ xfs_open_devices(
> error = xfs_blkdev_get(mp, mp->m_logname, &logdev);
> if (error)
> goto out;
> + dax_logdev = fs_dax_get_by_bdev(logdev);
> }
>
> if (mp->m_rtname) {
> @@ -765,24 +774,25 @@ xfs_open_devices(
> error = -EINVAL;
> goto out_close_rtdev;
> }
> + dax_rtdev = fs_dax_get_by_bdev(rtdev);
> }
>
> /*
> * Setup xfs_mount buffer target pointers
> */
> error = -ENOMEM;
> - mp->m_ddev_targp = xfs_alloc_buftarg(mp, ddev);
> + mp->m_ddev_targp = xfs_alloc_buftarg(mp, ddev, dax_ddev);
> if (!mp->m_ddev_targp)
> goto out_close_rtdev;
>
> if (rtdev) {
> - mp->m_rtdev_targp = xfs_alloc_buftarg(mp, rtdev);
> + mp->m_rtdev_targp = xfs_alloc_buftarg(mp, rtdev, dax_rtdev);
> if (!mp->m_rtdev_targp)
> goto out_free_ddev_targ;
> }
>
> if (logdev && logdev != ddev) {
> - mp->m_logdev_targp = xfs_alloc_buftarg(mp, logdev);
> + mp->m_logdev_targp = xfs_alloc_buftarg(mp, logdev, dax_logdev);
> if (!mp->m_logdev_targp)
> goto out_free_rtdev_targ;
> } else {
> @@ -798,9 +808,12 @@ xfs_open_devices(
> xfs_free_buftarg(mp, mp->m_ddev_targp);
> out_close_rtdev:
> xfs_blkdev_put(rtdev);
> + fs_put_dax(dax_rtdev);
> out_close_logdev:
> - if (logdev && logdev != ddev)
> + if (logdev && logdev != ddev) {
> xfs_blkdev_put(logdev);
> + fs_put_dax(dax_logdev);
> + }
> out:
> return error;
> }
> diff --git a/include/linux/dax.h b/include/linux/dax.h
> index df97b7af7e2c..6e32be3badec 100644
> --- a/include/linux/dax.h
> +++ b/include/linux/dax.h
> @@ -57,6 +57,7 @@ static inline void fs_put_dax(struct dax_device *dax_dev)
> put_dax(dax_dev);
> }
>
> +struct dax_device *fs_dax_get_by_bdev(struct block_device *bdev);
> #else
> static inline int bdev_dax_supported(struct super_block *sb, int blocksize)
> {
> @@ -71,6 +72,11 @@ static inline struct dax_device *fs_dax_get_by_host(const char *host)
> static inline void fs_put_dax(struct dax_device *dax_dev)
> {
> }
> +
> +struct dax_device *fs_dax_get_by_bdev(struct block_device *bdev)
> +{
> + return NULL;
> +}
> #endif
>
> int dax_read_lock(void);
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index 6e1fd5d21248..d0e3234a1fae 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -1334,6 +1334,7 @@ struct super_block {
> struct hlist_bl_head s_anon; /* anonymous dentries for (nfs) exporting */
> struct list_head s_mounts; /* list of mounts; _not_ for fs use */
> struct block_device *s_bdev;
> + struct dax_device *s_daxdev;
> struct backing_dev_info *s_bdi;
> struct mtd_info *s_mtd;
> struct hlist_node s_instances;
>
> --
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