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Message-ID: <20211226143439.3985960-2-ruansy.fnst@fujitsu.com>
Date: Sun, 26 Dec 2021 22:34:30 +0800
From: Shiyang Ruan <ruansy.fnst@...itsu.com>
To: <linux-kernel@...r.kernel.org>, <linux-xfs@...r.kernel.org>,
<nvdimm@...ts.linux.dev>, <linux-mm@...ck.org>,
<linux-fsdevel@...r.kernel.org>
CC: <djwong@...nel.org>, <dan.j.williams@...el.com>,
<david@...morbit.com>, <hch@...radead.org>, <jane.chu@...cle.com>
Subject: [PATCH v9 01/10] dax: Use percpu rwsem for dax_{read,write}_lock()
In order to introduce dax holder registration, we need a write lock for
dax. The write operation is per dax device job. So, the global lock is
not suitable. Change the current lock to percpu_rw_semaphore and introduce
a write lock for registration.
Signed-off-by: Shiyang Ruan <ruansy.fnst@...itsu.com>
---
drivers/dax/device.c | 11 +++++-----
drivers/dax/super.c | 42 ++++++++++++++++++++++++++------------
drivers/md/dm-writecache.c | 7 +++----
fs/dax.c | 31 ++++++++++++++--------------
fs/fuse/dax.c | 6 +++---
include/linux/dax.h | 19 ++++++++++++-----
6 files changed, 69 insertions(+), 47 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 e7152a6c4cc4..c46f56e33d40 100644
--- a/drivers/dax/super.c
+++ b/drivers/dax/super.c
@@ -26,29 +26,41 @@ struct dax_device {
struct inode inode;
struct cdev cdev;
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;
static struct super_block *dax_superblock __read_mostly;
-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);
+}
+EXPORT_SYMBOL_GPL(dax_write_lock);
+
+void dax_write_unlock(struct dax_device *dax_dev)
+{
+ percpu_up_write(&dax_dev->rwsem);
+}
+EXPORT_SYMBOL_GPL(dax_write_unlock);
+
#if defined(CONFIG_BLOCK) && defined(CONFIG_FS_DAX)
#include <linux/blkdev.h>
@@ -75,7 +87,7 @@ struct dax_device *fs_dax_get_by_bdev(struct block_device *bdev, u64 *start_off)
{
struct dax_device *dax_dev;
u64 part_size;
- int id;
+ bool not_found;
if (!blk_queue_dax(bdev->bd_disk->queue))
return NULL;
@@ -87,11 +99,14 @@ struct dax_device *fs_dax_get_by_bdev(struct block_device *bdev, u64 *start_off)
return NULL;
}
- id = dax_read_lock();
dax_dev = xa_load(&dax_hosts, (unsigned long)bdev->bd_disk);
- if (!dax_dev || !dax_alive(dax_dev) || !igrab(&dax_dev->inode))
- dax_dev = NULL;
- dax_read_unlock(id);
+ if (dax_dev) {
+ dax_read_lock(dax_dev);
+ not_found = !dax_alive(dax_dev) || !igrab(&dax_dev->inode);
+ dax_read_unlock(dax_dev);
+ if (not_found)
+ dax_dev = NULL;
+ }
return dax_dev;
}
@@ -222,7 +237,7 @@ 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);
@@ -237,9 +252,9 @@ 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);
}
EXPORT_SYMBOL_GPL(kill_dax);
@@ -366,6 +381,7 @@ struct dax_device *alloc_dax(void *private, const struct dax_operations *ops,
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 4f31591d2d25..ebe1ec345d1d 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 e0eecd8e3a8f..1f46810d4b68 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -717,20 +717,20 @@ static pgoff_t dax_iomap_pgoff(const struct iomap *iomap, loff_t pos)
static int copy_cow_page_dax(struct vm_fault *vmf, const struct iomap_iter *iter)
{
pgoff_t pgoff = dax_iomap_pgoff(&iter->iomap, iter->pos);
+ struct dax_device *dax_dev = iter->iomap.dax_dev;
void *vto, *kaddr;
long rc;
- int id;
- id = dax_read_lock();
- rc = dax_direct_access(iter->iomap.dax_dev, pgoff, 1, &kaddr, NULL);
+ 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(vmf->cow_page);
copy_user_page(vto, kaddr, vmf->address, vmf->cow_page);
kunmap_atomic(vto);
- dax_read_unlock(id);
+ dax_read_unlock(dax_dev);
return 0;
}
@@ -1009,10 +1009,10 @@ static int dax_iomap_pfn(const struct iomap *iomap, loff_t pos, size_t size,
pfn_t *pfnp)
{
pgoff_t pgoff = dax_iomap_pgoff(iomap, pos);
- int id, rc;
+ int rc;
long length;
- 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) {
@@ -1029,7 +1029,7 @@ 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;
}
@@ -1135,6 +1135,7 @@ static s64 dax_zero_iter(struct iomap_iter *iter, bool *did_zero)
{
const struct iomap *iomap = &iter->iomap;
const struct iomap *srcmap = iomap_iter_srcmap(iter);
+ struct dax_device *dax_dev = iomap->dax_dev;
loff_t pos = iter->pos;
u64 length = iomap_length(iter);
s64 written = 0;
@@ -1148,14 +1149,13 @@ static s64 dax_zero_iter(struct iomap_iter *iter, bool *did_zero)
unsigned size = min_t(u64, PAGE_SIZE - offset, length);
pgoff_t pgoff = dax_iomap_pgoff(iomap, pos);
long rc;
- int id;
- id = dax_read_lock();
+ dax_read_lock(dax_dev);
if (IS_ALIGNED(pos, PAGE_SIZE) && size == PAGE_SIZE)
- rc = dax_zero_page_range(iomap->dax_dev, pgoff, 1);
+ rc = dax_zero_page_range(dax_dev, pgoff, 1);
else
- rc = dax_memzero(iomap->dax_dev, pgoff, offset, size);
- dax_read_unlock(id);
+ rc = dax_memzero(dax_dev, pgoff, offset, size);
+ dax_read_unlock(dax_dev);
if (rc < 0)
return rc;
@@ -1209,7 +1209,6 @@ 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));
@@ -1234,7 +1233,7 @@ 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);
@@ -1281,7 +1280,7 @@ 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/fs/fuse/dax.c b/fs/fuse/dax.c
index 713818d74de6..00a419acab79 100644
--- a/fs/fuse/dax.c
+++ b/fs/fuse/dax.c
@@ -1231,7 +1231,7 @@ static int fuse_dax_mem_range_init(struct fuse_conn_dax *fcd)
{
long nr_pages, nr_ranges;
struct fuse_dax_mapping *range;
- int ret, id;
+ int ret;
size_t dax_size = -1;
unsigned long i;
@@ -1240,10 +1240,10 @@ static int fuse_dax_mem_range_init(struct fuse_conn_dax *fcd)
INIT_LIST_HEAD(&fcd->busy_ranges);
INIT_DELAYED_WORK(&fcd->free_work, fuse_dax_free_mem_worker);
- id = dax_read_lock();
+ dax_read_lock(fcd->dev);
nr_pages = dax_direct_access(fcd->dev, 0, PHYS_PFN(dax_size), NULL,
NULL);
- dax_read_unlock(id);
+ dax_read_unlock(fcd->dev);
if (nr_pages < 0) {
pr_debug("dax_direct_access() returned %ld\n", nr_pages);
return nr_pages;
diff --git a/include/linux/dax.h b/include/linux/dax.h
index 87ae4c9b1d65..a146bfb80804 100644
--- a/include/linux/dax.h
+++ b/include/linux/dax.h
@@ -178,15 +178,24 @@ int dax_truncate_page(struct inode *inode, loff_t pos, bool *did_zero,
const struct iomap_ops *ops);
#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);
+void dax_write_lock(struct dax_device *dax_dev);
+void dax_write_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)
+{
+}
+
+static inline void dax_read_unlock(struct dax_device *dax_dev)
+{
+}
+
+static inline void dax_write_lock(struct dax_device *dax_dev)
{
- return 0;
}
-static inline void dax_read_unlock(int id)
+static inline void dax_write_unlock(struct dax_device *dax_dev)
{
}
#endif /* CONFIG_DAX */
--
2.34.1
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