Towards solving DAX-DMA vs truncate arrange for filesystems to set up a page-idle callback when they mount a dax_device.
No functional changes are expected as this only registers a nop handler for the ->page_free() event for device-mapped pages. Cc: "Jérôme Glisse" <[email protected]> Cc: Michal Hocko <[email protected]> Signed-off-by: Dan Williams <[email protected]> --- drivers/dax/super.c | 80 ++++++++++++++++++++++++++++++++++++++++------ drivers/nvdimm/pmem.c | 13 +++++++ fs/ext2/super.c | 6 ++- fs/ext4/super.c | 6 ++- fs/xfs/xfs_super.c | 20 ++++++------ include/linux/dax.h | 17 +++++----- include/linux/memremap.h | 6 +++ kernel/memremap.c | 1 + 8 files changed, 113 insertions(+), 36 deletions(-) diff --git a/drivers/dax/super.c b/drivers/dax/super.c index 3ccb064d200d..193e0cd8d90c 100644 --- a/drivers/dax/super.c +++ b/drivers/dax/super.c @@ -29,6 +29,7 @@ static struct vfsmount *dax_mnt; static DEFINE_IDA(dax_minor_ida); static struct kmem_cache *dax_cache __read_mostly; static struct super_block *dax_superblock __read_mostly; +DEFINE_MUTEX(devmap_lock); #define DAX_HASH_SIZE (PAGE_SIZE / sizeof(struct hlist_head)) static struct hlist_head dax_host_list[DAX_HASH_SIZE]; @@ -62,16 +63,6 @@ int bdev_dax_pgoff(struct block_device *bdev, sector_t sector, size_t size, } EXPORT_SYMBOL(bdev_dax_pgoff); -#if IS_ENABLED(CONFIG_FS_DAX) -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); -#endif - /** * __bdev_dax_supported() - Check if the device supports dax for filesystem * @sb: The superblock of the device @@ -169,9 +160,65 @@ struct dax_device { const char *host; void *private; unsigned long flags; + struct dev_pagemap *pgmap; const struct dax_operations *ops; }; +#if IS_ENABLED(CONFIG_FS_DAX) +static void generic_dax_pagefree(struct page *page, void *data) +{ +} + +struct dax_device *fs_dax_claim_bdev(struct block_device *bdev, void *owner) +{ + struct dax_device *dax_dev; + struct dev_pagemap *pgmap; + + if (!blk_queue_dax(bdev->bd_queue)) + return NULL; + dax_dev = fs_dax_get_by_host(bdev->bd_disk->disk_name); + if (!dax_dev->pgmap) + return dax_dev; + pgmap = dax_dev->pgmap; + + mutex_lock(&devmap_lock); + if ((pgmap->data && pgmap->data != owner) || pgmap->page_free + || pgmap->page_fault + || pgmap->type != MEMORY_DEVICE_HOST) { + put_dax(dax_dev); + mutex_unlock(&devmap_lock); + return NULL; + } + + pgmap->type = MEMORY_DEVICE_FS_DAX; + pgmap->page_free = generic_dax_pagefree; + pgmap->data = owner; + mutex_unlock(&devmap_lock); + + return dax_dev; +} +EXPORT_SYMBOL_GPL(fs_dax_claim_bdev); + +void fs_dax_release(struct dax_device *dax_dev, void *owner) +{ + struct dev_pagemap *pgmap = dax_dev ? dax_dev->pgmap : NULL; + + put_dax(dax_dev); + if (!pgmap) + return; + if (!pgmap->data) + return; + + mutex_lock(&devmap_lock); + WARN_ON(pgmap->data != owner); + pgmap->type = MEMORY_DEVICE_HOST; + pgmap->page_free = NULL; + pgmap->data = NULL; + mutex_unlock(&devmap_lock); +} +EXPORT_SYMBOL_GPL(fs_dax_release); +#endif + static ssize_t write_cache_show(struct device *dev, struct device_attribute *attr, char *buf) { @@ -502,10 +549,23 @@ struct dax_device *alloc_dax(void *private, const char *__host, } EXPORT_SYMBOL_GPL(alloc_dax); +struct dax_device *alloc_dax_devmap(void *private, const char *host, + const struct dax_operations *ops, struct dev_pagemap *pgmap) +{ + struct dax_device *dax_dev = alloc_dax(private, host, ops); + + if (dax_dev) + dax_dev->pgmap = pgmap; + return dax_dev; +} +EXPORT_SYMBOL_GPL(alloc_dax_devmap); + void put_dax(struct dax_device *dax_dev) { if (!dax_dev) return; + put_dev_pagemap(dax_dev->pgmap); + dax_dev->pgmap = NULL; iput(&dax_dev->inode); } EXPORT_SYMBOL_GPL(put_dax); diff --git a/drivers/nvdimm/pmem.c b/drivers/nvdimm/pmem.c index 39dfd7affa31..9f36a2193eb6 100644 --- a/drivers/nvdimm/pmem.c +++ b/drivers/nvdimm/pmem.c @@ -300,6 +300,7 @@ static int pmem_attach_disk(struct device *dev, struct vmem_altmap __altmap, *altmap = NULL; int nid = dev_to_node(dev), fua, wbc; struct resource *res = &nsio->res; + struct dev_pagemap *pgmap = NULL; struct nd_pfn *nd_pfn = NULL; struct dax_device *dax_dev; struct nd_pfn_sb *pfn_sb; @@ -358,14 +359,24 @@ static int pmem_attach_disk(struct device *dev, pmem->pfn_flags |= PFN_MAP; res = &pfn_res; /* for badblocks populate */ res->start += pmem->data_offset; + pgmap = get_dev_pagemap(PHYS_PFN(virt_to_phys(addr)), NULL); + if (!pgmap) + return -ENOMEM; } else if (pmem_should_map_pages(dev)) { addr = devm_memremap_pages(dev, &nsio->res, &q->q_usage_counter, NULL); pmem->pfn_flags |= PFN_MAP; + pgmap = get_dev_pagemap(PHYS_PFN(virt_to_phys(addr)), NULL); + if (!pgmap) + return -ENOMEM; } else addr = devm_memremap(dev, pmem->phys_addr, pmem->size, ARCH_MEMREMAP_PMEM); + + /* we still hold a reference until the driver is unloaded */ + put_dev_pagemap(pgmap); + /* * At release time the queue must be frozen before * devm_memremap_pages is unwound @@ -402,7 +413,7 @@ static int pmem_attach_disk(struct device *dev, nvdimm_badblocks_populate(nd_region, &pmem->bb, res); disk->bb = &pmem->bb; - dax_dev = alloc_dax(pmem, disk->disk_name, &pmem_dax_ops); + dax_dev = alloc_dax_devmap(pmem, disk->disk_name, &pmem_dax_ops, pgmap); if (!dax_dev) { put_disk(disk); return -ENOMEM; diff --git a/fs/ext2/super.c b/fs/ext2/super.c index 1458706bd2ec..884784acd9fd 100644 --- a/fs/ext2/super.c +++ b/fs/ext2/super.c @@ -171,7 +171,7 @@ static void ext2_put_super (struct super_block * sb) brelse (sbi->s_sbh); sb->s_fs_info = NULL; kfree(sbi->s_blockgroup_lock); - fs_put_dax(sbi->s_daxdev); + fs_dax_release(sbi->s_daxdev, sb); kfree(sbi); } @@ -814,7 +814,7 @@ static unsigned long descriptor_loc(struct super_block *sb, static int ext2_fill_super(struct super_block *sb, void *data, int silent) { - struct dax_device *dax_dev = fs_dax_get_by_bdev(sb->s_bdev); + struct dax_device *dax_dev = fs_dax_claim_bdev(sb->s_bdev, sb); struct buffer_head * bh; struct ext2_sb_info * sbi; struct ext2_super_block * es; @@ -1202,7 +1202,7 @@ static int ext2_fill_super(struct super_block *sb, void *data, int silent) kfree(sbi->s_blockgroup_lock); kfree(sbi); failed: - fs_put_dax(dax_dev); + fs_dax_release(dax_dev, sb); return ret; } diff --git a/fs/ext4/super.c b/fs/ext4/super.c index b104096fce9e..f27355f41616 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -950,7 +950,7 @@ static void ext4_put_super(struct super_block *sb) if (sbi->s_chksum_driver) crypto_free_shash(sbi->s_chksum_driver); kfree(sbi->s_blockgroup_lock); - fs_put_dax(sbi->s_daxdev); + fs_dax_release(sbi->s_daxdev, sb); kfree(sbi); } @@ -3397,7 +3397,7 @@ static void ext4_set_resv_clusters(struct super_block *sb) static int ext4_fill_super(struct super_block *sb, void *data, int silent) { - struct dax_device *dax_dev = fs_dax_get_by_bdev(sb->s_bdev); + struct dax_device *dax_dev = fs_dax_claim_bdev(sb->s_bdev, sb); char *orig_data = kstrdup(data, GFP_KERNEL); struct buffer_head *bh; struct ext4_super_block *es = NULL; @@ -4400,7 +4400,7 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent) out_free_base: kfree(sbi); kfree(orig_data); - fs_put_dax(dax_dev); + fs_dax_release(dax_dev, sb); return err ? err : ret; } diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c index 584cf2d573ba..fdc4785a5c85 100644 --- a/fs/xfs/xfs_super.c +++ b/fs/xfs/xfs_super.c @@ -722,7 +722,7 @@ xfs_close_devices( xfs_free_buftarg(mp, mp->m_logdev_targp); xfs_blkdev_put(logdev); - fs_put_dax(dax_logdev); + fs_dax_release(dax_logdev, mp); } if (mp->m_rtdev_targp) { struct block_device *rtdev = mp->m_rtdev_targp->bt_bdev; @@ -730,10 +730,10 @@ xfs_close_devices( xfs_free_buftarg(mp, mp->m_rtdev_targp); xfs_blkdev_put(rtdev); - fs_put_dax(dax_rtdev); + fs_dax_release(dax_rtdev, mp); } xfs_free_buftarg(mp, mp->m_ddev_targp); - fs_put_dax(dax_ddev); + fs_dax_release(dax_ddev, mp); } /* @@ -751,9 +751,9 @@ xfs_open_devices( struct xfs_mount *mp) { struct block_device *ddev = mp->m_super->s_bdev; - struct dax_device *dax_ddev = fs_dax_get_by_bdev(ddev); - struct dax_device *dax_logdev = NULL, *dax_rtdev = NULL; + struct dax_device *dax_ddev = fs_dax_claim_bdev(ddev, mp); struct block_device *logdev = NULL, *rtdev = NULL; + struct dax_device *dax_logdev = NULL, *dax_rtdev = NULL; int error; /* @@ -763,7 +763,7 @@ xfs_open_devices( error = xfs_blkdev_get(mp, mp->m_logname, &logdev); if (error) goto out; - dax_logdev = fs_dax_get_by_bdev(logdev); + dax_logdev = fs_dax_claim_bdev(logdev, mp); } if (mp->m_rtname) { @@ -777,7 +777,7 @@ xfs_open_devices( error = -EINVAL; goto out_close_rtdev; } - dax_rtdev = fs_dax_get_by_bdev(rtdev); + dax_rtdev = fs_dax_claim_bdev(rtdev, mp); } /* @@ -811,14 +811,14 @@ xfs_open_devices( xfs_free_buftarg(mp, mp->m_ddev_targp); out_close_rtdev: xfs_blkdev_put(rtdev); - fs_put_dax(dax_rtdev); + fs_dax_release(dax_rtdev, mp); out_close_logdev: if (logdev && logdev != ddev) { xfs_blkdev_put(logdev); - fs_put_dax(dax_logdev); + fs_dax_release(dax_logdev, mp); } out: - fs_put_dax(dax_ddev); + fs_dax_release(dax_ddev, mp); return error; } diff --git a/include/linux/dax.h b/include/linux/dax.h index 122197124b9d..ea21ebfd1889 100644 --- a/include/linux/dax.h +++ b/include/linux/dax.h @@ -50,12 +50,8 @@ static inline struct dax_device *fs_dax_get_by_host(const char *host) return dax_get_by_host(host); } -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); +struct dax_device *fs_dax_claim_bdev(struct block_device *bdev, void *owner); +void fs_dax_release(struct dax_device *dax_dev, void *owner); #else static inline int bdev_dax_supported(struct super_block *sb, int blocksize) { @@ -67,13 +63,14 @@ static inline struct dax_device *fs_dax_get_by_host(const char *host) return NULL; } -static inline void fs_put_dax(struct dax_device *dax_dev) +static inline struct dax_device *fs_dax_claim_bdev(struct block_device *bdev, + void *owner) { + return NULL; } -static inline struct dax_device *fs_dax_get_by_bdev(struct block_device *bdev) +static inline void fs_dax_release(struct dax_device *dax_dev, void *owner) { - return NULL; } #endif @@ -81,6 +78,8 @@ int dax_read_lock(void); void dax_read_unlock(int id); struct dax_device *alloc_dax(void *private, const char *host, const struct dax_operations *ops); +struct dax_device *alloc_dax_devmap(void *private, const char *host, + const struct dax_operations *ops, struct dev_pagemap *pgmap); bool dax_alive(struct dax_device *dax_dev); void kill_dax(struct dax_device *dax_dev); void *dax_get_private(struct dax_device *dax_dev); diff --git a/include/linux/memremap.h b/include/linux/memremap.h index 79f8ba7c3894..39d2de3f744b 100644 --- a/include/linux/memremap.h +++ b/include/linux/memremap.h @@ -64,11 +64,17 @@ static inline struct vmem_altmap *to_vmem_altmap(unsigned long memmap_start) * driver can hotplug the device memory using ZONE_DEVICE and with that memory * type. Any page of a process can be migrated to such memory. However no one * should be allow to pin such memory so that it can always be evicted. + * + * MEMORY_DEVICE_FS_DAX: + * MEMORY_DEVICE_HOST memory that is being managed by a filesystem. The + * filesystem needs page idle callbacks to coordinate direct-I/O + DMA + * (get_user_pages) vs truncate. */ enum memory_type { MEMORY_DEVICE_HOST = 0, MEMORY_DEVICE_PRIVATE, MEMORY_DEVICE_PUBLIC, + MEMORY_DEVICE_FS_DAX, }; /* diff --git a/kernel/memremap.c b/kernel/memremap.c index 403ab9cdb949..bf61cfa89c7d 100644 --- a/kernel/memremap.c +++ b/kernel/memremap.c @@ -323,6 +323,7 @@ struct dev_pagemap *find_dev_pagemap(resource_size_t phys) page_map = radix_tree_lookup(&pgmap_radix, PHYS_PFN(phys)); return page_map ? &page_map->pgmap : NULL; } +EXPORT_SYMBOL_GPL(find_dev_pagemap); /** * devm_memremap_pages - remap and provide memmap backing for the given resource
