In order to introduce dax holder registration, we need a write lock for dax. Change the current lock to percpu_rw_semaphore and introduce a dax write lock for registration.
Signed-off-by: Shiyang Ruan <ruansy.f...@fujitsu.com> --- drivers/dax/device.c | 11 ++++---- drivers/dax/super.c | 51 +++++++++++++++++++++++--------------- drivers/md/dm-writecache.c | 7 +++--- fs/dax.c | 26 +++++++++---------- include/linux/dax.h | 9 +++---- 5 files changed, 55 insertions(+), 49 deletions(-) diff --git a/drivers/dax/device.c b/drivers/dax/device.c index dd8222a42808..041345f9956d 100644 --- a/drivers/dax/device.c +++ b/drivers/dax/device.c @@ -198,7 +198,6 @@ static vm_fault_t dev_dax_huge_fault(struct vm_fault *vmf, struct file *filp = vmf->vma->vm_file; unsigned long fault_size; vm_fault_t rc = VM_FAULT_SIGBUS; - int id; pfn_t pfn; struct dev_dax *dev_dax = filp->private_data; @@ -206,7 +205,7 @@ static vm_fault_t dev_dax_huge_fault(struct vm_fault *vmf, (vmf->flags & FAULT_FLAG_WRITE) ? "write" : "read", vmf->vma->vm_start, vmf->vma->vm_end, pe_size); - id = dax_read_lock(); + dax_read_lock(dev_dax->dax_dev); switch (pe_size) { case PE_SIZE_PTE: fault_size = PAGE_SIZE; @@ -246,7 +245,7 @@ static vm_fault_t dev_dax_huge_fault(struct vm_fault *vmf, page->index = pgoff + i; } } - dax_read_unlock(id); + dax_read_unlock(dev_dax->dax_dev); return rc; } @@ -284,7 +283,7 @@ static const struct vm_operations_struct dax_vm_ops = { static int dax_mmap(struct file *filp, struct vm_area_struct *vma) { struct dev_dax *dev_dax = filp->private_data; - int rc, id; + int rc; dev_dbg(&dev_dax->dev, "trace\n"); @@ -292,9 +291,9 @@ static int dax_mmap(struct file *filp, struct vm_area_struct *vma) * We lock to check dax_dev liveness and will re-check at * fault time. */ - id = dax_read_lock(); + dax_read_lock(dev_dax->dax_dev); rc = check_vma(dev_dax, vma, __func__); - dax_read_unlock(id); + dax_read_unlock(dev_dax->dax_dev); if (rc) return rc; diff --git a/drivers/dax/super.c b/drivers/dax/super.c index fc89e91beea7..f7701e943019 100644 --- a/drivers/dax/super.c +++ b/drivers/dax/super.c @@ -31,12 +31,12 @@ struct dax_device { struct cdev cdev; const char *host; void *private; + struct percpu_rw_semaphore rwsem; unsigned long flags; const struct dax_operations *ops; }; static dev_t dax_devt; -DEFINE_STATIC_SRCU(dax_srcu); static struct vfsmount *dax_mnt; static DEFINE_IDA(dax_minor_ida); static struct kmem_cache *dax_cache __read_mostly; @@ -46,18 +46,28 @@ static struct super_block *dax_superblock __read_mostly; static struct hlist_head dax_host_list[DAX_HASH_SIZE]; static DEFINE_SPINLOCK(dax_host_lock); -int dax_read_lock(void) +void dax_read_lock(struct dax_device *dax_dev) { - return srcu_read_lock(&dax_srcu); + percpu_down_read(&dax_dev->rwsem); } EXPORT_SYMBOL_GPL(dax_read_lock); -void dax_read_unlock(int id) +void dax_read_unlock(struct dax_device *dax_dev) { - srcu_read_unlock(&dax_srcu, id); + percpu_up_read(&dax_dev->rwsem); } EXPORT_SYMBOL_GPL(dax_read_unlock); +void dax_write_lock(struct dax_device *dax_dev) +{ + percpu_down_write(&dax_dev->rwsem); +} + +void dax_write_unlock(struct dax_device *dax_dev) +{ + percpu_up_write(&dax_dev->rwsem); +} + static int dax_host_hash(const char *host) { return hashlen_hash(hashlen_string("DAX", host)) % DAX_HASH_SIZE; @@ -70,26 +80,28 @@ static int dax_host_hash(const char *host) static struct dax_device *dax_get_by_host(const char *host) { struct dax_device *dax_dev, *found = NULL; - int hash, id; + int hash; if (!host) return NULL; hash = dax_host_hash(host); - id = dax_read_lock(); spin_lock(&dax_host_lock); hlist_for_each_entry(dax_dev, &dax_host_list[hash], list) { + dax_read_lock(dax_dev); if (!dax_alive(dax_dev) - || strcmp(host, dax_dev->host) != 0) + || strcmp(host, dax_dev->host) != 0) { + dax_read_unlock(dax_dev); continue; + } if (igrab(&dax_dev->inode)) found = dax_dev; + dax_read_unlock(dax_dev); break; } spin_unlock(&dax_host_lock); - dax_read_unlock(id); return found; } @@ -130,7 +142,7 @@ bool generic_fsdax_supported(struct dax_device *dax_dev, pfn_t pfn, end_pfn; sector_t last_page; long len, len2; - int err, id; + int err; if (blocksize != PAGE_SIZE) { pr_info("%pg: error: unsupported blocksize for dax\n", bdev); @@ -155,14 +167,14 @@ bool generic_fsdax_supported(struct dax_device *dax_dev, return false; } - id = dax_read_lock(); + dax_read_lock(dax_dev); len = dax_direct_access(dax_dev, pgoff, 1, &kaddr, &pfn); len2 = dax_direct_access(dax_dev, pgoff_end, 1, &end_kaddr, &end_pfn); if (len < 1 || len2 < 1) { pr_info("%pg: error: dax access failed (%ld)\n", bdev, len < 1 ? len : len2); - dax_read_unlock(id); + dax_read_unlock(dax_dev); return false; } @@ -192,7 +204,7 @@ bool generic_fsdax_supported(struct dax_device *dax_dev, put_dev_pagemap(end_pgmap); } - dax_read_unlock(id); + dax_read_unlock(dax_dev); if (!dax_enabled) { pr_info("%pg: error: dax support not enabled\n", bdev); @@ -206,16 +218,15 @@ bool dax_supported(struct dax_device *dax_dev, struct block_device *bdev, int blocksize, sector_t start, sector_t len) { bool ret = false; - int id; if (!dax_dev) return false; - id = dax_read_lock(); + dax_read_lock(dax_dev); if (dax_alive(dax_dev) && dax_dev->ops->dax_supported) ret = dax_dev->ops->dax_supported(dax_dev, bdev, blocksize, start, len); - dax_read_unlock(id); + dax_read_unlock(dax_dev); return ret; } EXPORT_SYMBOL_GPL(dax_supported); @@ -410,7 +421,7 @@ EXPORT_SYMBOL_GPL(__set_dax_synchronous); bool dax_alive(struct dax_device *dax_dev) { - lockdep_assert_held(&dax_srcu); + lockdep_assert_held(&dax_dev->rwsem); return test_bit(DAXDEV_ALIVE, &dax_dev->flags); } EXPORT_SYMBOL_GPL(dax_alive); @@ -425,10 +436,9 @@ void kill_dax(struct dax_device *dax_dev) { if (!dax_dev) return; - + dax_write_lock(dax_dev); clear_bit(DAXDEV_ALIVE, &dax_dev->flags); - - synchronize_srcu(&dax_srcu); + dax_write_unlock(dax_dev); spin_lock(&dax_host_lock); hlist_del_init(&dax_dev->list); @@ -590,6 +600,7 @@ struct dax_device *alloc_dax(void *private, const char *__host, dax_add_host(dax_dev, host); dax_dev->ops = ops; dax_dev->private = private; + percpu_init_rwsem(&dax_dev->rwsem); if (flags & DAXDEV_F_SYNC) set_dax_synchronous(dax_dev); diff --git a/drivers/md/dm-writecache.c b/drivers/md/dm-writecache.c index 18320444fb0a..abce88bf1b24 100644 --- a/drivers/md/dm-writecache.c +++ b/drivers/md/dm-writecache.c @@ -260,7 +260,6 @@ static int persistent_memory_claim(struct dm_writecache *wc) loff_t s; long p, da; pfn_t pfn; - int id; struct page **pages; sector_t offset; @@ -284,7 +283,7 @@ static int persistent_memory_claim(struct dm_writecache *wc) } offset >>= PAGE_SHIFT - 9; - id = dax_read_lock(); + dax_read_lock(wc->ssd_dev->dax_dev); da = dax_direct_access(wc->ssd_dev->dax_dev, offset, p, &wc->memory_map, &pfn); if (da < 0) { @@ -334,7 +333,7 @@ static int persistent_memory_claim(struct dm_writecache *wc) wc->memory_vmapped = true; } - dax_read_unlock(id); + dax_read_unlock(wc->ssd_dev->dax_dev); wc->memory_map += (size_t)wc->start_sector << SECTOR_SHIFT; wc->memory_map_size -= (size_t)wc->start_sector << SECTOR_SHIFT; @@ -343,7 +342,7 @@ static int persistent_memory_claim(struct dm_writecache *wc) err3: kvfree(pages); err2: - dax_read_unlock(id); + dax_read_unlock(wc->ssd_dev->dax_dev); err1: return r; } diff --git a/fs/dax.c b/fs/dax.c index 4e3e5a283a91..a06cbb950950 100644 --- a/fs/dax.c +++ b/fs/dax.c @@ -715,22 +715,21 @@ static int copy_cow_page_dax(struct block_device *bdev, struct dax_device *dax_d void *vto, *kaddr; pgoff_t pgoff; long rc; - int id; rc = bdev_dax_pgoff(bdev, sector, PAGE_SIZE, &pgoff); if (rc) return rc; - id = dax_read_lock(); + dax_read_lock(dax_dev); rc = dax_direct_access(dax_dev, pgoff, 1, &kaddr, NULL); if (rc < 0) { - dax_read_unlock(id); + dax_read_unlock(dax_dev); return rc; } vto = kmap_atomic(to); copy_user_page(vto, (void __force *)kaddr, vaddr, to); kunmap_atomic(vto); - dax_read_unlock(id); + dax_read_unlock(dax_dev); return 0; } @@ -1015,13 +1014,13 @@ static int dax_iomap_pfn(const struct iomap *iomap, loff_t pos, size_t size, { const sector_t sector = dax_iomap_sector(iomap, pos); pgoff_t pgoff; - int id, rc; + int rc; long length; rc = bdev_dax_pgoff(iomap->bdev, sector, size, &pgoff); if (rc) return rc; - id = dax_read_lock(); + dax_read_lock(iomap->dax_dev); length = dax_direct_access(iomap->dax_dev, pgoff, PHYS_PFN(size), NULL, pfnp); if (length < 0) { @@ -1038,7 +1037,7 @@ static int dax_iomap_pfn(const struct iomap *iomap, loff_t pos, size_t size, goto out; rc = 0; out: - dax_read_unlock(id); + dax_read_unlock(iomap->dax_dev); return rc; } @@ -1130,7 +1129,7 @@ s64 dax_iomap_zero(loff_t pos, u64 length, struct iomap *iomap) { sector_t sector = iomap_sector(iomap, pos & PAGE_MASK); pgoff_t pgoff; - long rc, id; + long rc; void *kaddr; bool page_aligned = false; unsigned offset = offset_in_page(pos); @@ -1144,14 +1143,14 @@ s64 dax_iomap_zero(loff_t pos, u64 length, struct iomap *iomap) if (rc) return rc; - id = dax_read_lock(); + dax_read_lock(iomap->dax_dev); if (page_aligned) rc = dax_zero_page_range(iomap->dax_dev, pgoff, 1); else rc = dax_direct_access(iomap->dax_dev, pgoff, 1, &kaddr, NULL); if (rc < 0) { - dax_read_unlock(id); + dax_read_unlock(iomap->dax_dev); return rc; } @@ -1159,7 +1158,7 @@ s64 dax_iomap_zero(loff_t pos, u64 length, struct iomap *iomap) memset(kaddr + offset, 0, size); dax_flush(iomap->dax_dev, kaddr + offset, size); } - dax_read_unlock(id); + dax_read_unlock(iomap->dax_dev); return size; } @@ -1174,7 +1173,6 @@ static loff_t dax_iomap_iter(const struct iomap_iter *iomi, loff_t end = pos + length, done = 0; ssize_t ret = 0; size_t xfer; - int id; if (iov_iter_rw(iter) == READ) { end = min(end, i_size_read(iomi->inode)); @@ -1199,7 +1197,7 @@ static loff_t dax_iomap_iter(const struct iomap_iter *iomi, (end - 1) >> PAGE_SHIFT); } - id = dax_read_lock(); + dax_read_lock(dax_dev); while (pos < end) { unsigned offset = pos & (PAGE_SIZE - 1); const size_t size = ALIGN(length + offset, PAGE_SIZE); @@ -1251,7 +1249,7 @@ static loff_t dax_iomap_iter(const struct iomap_iter *iomi, if (xfer < map_len) break; } - dax_read_unlock(id); + dax_read_unlock(dax_dev); return done ? done : ret; } diff --git a/include/linux/dax.h b/include/linux/dax.h index 2619d94c308d..e38711d6c519 100644 --- a/include/linux/dax.h +++ b/include/linux/dax.h @@ -177,15 +177,14 @@ static inline void dax_unlock_page(struct page *page, dax_entry_t cookie) #endif #if IS_ENABLED(CONFIG_DAX) -int dax_read_lock(void); -void dax_read_unlock(int id); +void dax_read_lock(struct dax_device *dax_dev); +void dax_read_unlock(struct dax_device *dax_dev); #else -static inline int dax_read_lock(void) +static inline void dax_read_lock(struct dax_device *dax_dev) { - return 0; } -static inline void dax_read_unlock(int id) +static inline void dax_read_unlock(struct dax_device *dax_dev) { } #endif /* CONFIG_DAX */ -- 2.33.0