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Subject[PATCH 20/20] fuse,virtiofs: Add logic to free up a memory range
Date
Add logic to free up a busy memory range. Freed memory range will be
returned to free pool. Add a worker which can be started to select
and free some busy memory ranges.

Process can also steal one of its busy dax ranges if free range is not
available. I will refer it to as direct reclaim.

If free range is not available and nothing can't be stolen from same
inode, caller waits on a waitq for free range to become available.

For reclaiming a range, as of now we need to hold following locks in
specified order.

down_write(&fi->i_mmap_sem);
down_write(&fi->i_dmap_sem);

We look for a free range in following order.

A. Try to get a free range.
B. If not, try direct reclaim.
C. If not, wait for a memory range to become free

Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Liu Bo <bo.liu@linux.alibaba.com>
---
fs/fuse/file.c | 450 ++++++++++++++++++++++++++++++++++++++++++++++-
fs/fuse/fuse_i.h | 25 +++
fs/fuse/inode.c | 5 +
3 files changed, 473 insertions(+), 7 deletions(-)

diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index 8b264fcb9b3c..61ae2ddeef55 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -8,6 +8,7 @@

#include "fuse_i.h"

+#include <linux/delay.h>
#include <linux/pagemap.h>
#include <linux/slab.h>
#include <linux/kernel.h>
@@ -37,6 +38,8 @@ static struct page **fuse_pages_alloc(unsigned int npages, gfp_t flags,
return pages;
}

+static struct fuse_dax_mapping *alloc_dax_mapping_reclaim(struct fuse_conn *fc,
+ struct inode *inode, bool fault);
static int fuse_send_open(struct fuse_conn *fc, u64 nodeid, struct file *file,
int opcode, struct fuse_open_out *outargp)
{
@@ -193,6 +196,28 @@ static void fuse_link_write_file(struct file *file)
spin_unlock(&fi->lock);
}

+static void
+__kick_dmap_free_worker(struct fuse_conn *fc, unsigned long delay_ms)
+{
+ unsigned long free_threshold;
+
+ /* If number of free ranges are below threshold, start reclaim */
+ free_threshold = max((fc->nr_ranges * FUSE_DAX_RECLAIM_THRESHOLD)/100,
+ (unsigned long)1);
+ if (fc->nr_free_ranges < free_threshold) {
+ pr_debug("fuse: Kicking dax memory reclaim worker. nr_free_ranges=0x%ld nr_total_ranges=%ld\n", fc->nr_free_ranges, fc->nr_ranges);
+ queue_delayed_work(system_long_wq, &fc->dax_free_work,
+ msecs_to_jiffies(delay_ms));
+ }
+}
+
+static void kick_dmap_free_worker(struct fuse_conn *fc, unsigned long delay_ms)
+{
+ spin_lock(&fc->lock);
+ __kick_dmap_free_worker(fc, delay_ms);
+ spin_unlock(&fc->lock);
+}
+
static struct fuse_dax_mapping *alloc_dax_mapping(struct fuse_conn *fc)
{
struct fuse_dax_mapping *dmap = NULL;
@@ -201,7 +226,7 @@ static struct fuse_dax_mapping *alloc_dax_mapping(struct fuse_conn *fc)

if (fc->nr_free_ranges <= 0) {
spin_unlock(&fc->lock);
- return NULL;
+ goto out_kick;
}

WARN_ON(list_empty(&fc->free_ranges));
@@ -212,6 +237,9 @@ static struct fuse_dax_mapping *alloc_dax_mapping(struct fuse_conn *fc)
list_del_init(&dmap->list);
fc->nr_free_ranges--;
spin_unlock(&fc->lock);
+
+out_kick:
+ kick_dmap_free_worker(fc, 0);
return dmap;
}

@@ -238,6 +266,7 @@ static void __dmap_add_to_free_pool(struct fuse_conn *fc,
{
list_add_tail(&dmap->list, &fc->free_ranges);
fc->nr_free_ranges++;
+ wake_up(&fc->dax_range_waitq);
}

static void dmap_add_to_free_pool(struct fuse_conn *fc,
@@ -289,6 +318,12 @@ static int fuse_setup_one_mapping(struct inode *inode, loff_t offset,

dmap->writable = writable;
if (!upgrade) {
+ /*
+ * We don't take a refernce on inode. inode is valid right now
+ * and when inode is going away, cleanup logic should first
+ * cleanup dmap entries.
+ */
+ dmap->inode = inode;
dmap->start = offset;
dmap->end = offset + FUSE_DAX_MEM_RANGE_SZ - 1;
/* Protected by fi->i_dmap_sem */
@@ -368,6 +403,7 @@ static void dmap_reinit_add_to_free_pool(struct fuse_conn *fc,
"window_offset=0x%llx length=0x%llx\n", dmap->start,
dmap->end, dmap->window_offset, dmap->length);
__dmap_remove_busy_list(fc, dmap);
+ dmap->inode = NULL;
dmap->start = dmap->end = 0;
__dmap_add_to_free_pool(fc, dmap);
}
@@ -386,7 +422,8 @@ static void inode_reclaim_dmap_range(struct fuse_conn *fc, struct inode *inode,
int err, num = 0;
LIST_HEAD(to_remove);

- pr_debug("fuse: %s: start=0x%llx, end=0x%llx\n", __func__, start, end);
+ pr_debug("fuse: %s: inode=0x%px start=0x%llx, end=0x%llx\n", __func__,
+ inode, start, end);

/*
* Interval tree search matches intersecting entries. Adjust the range
@@ -400,6 +437,8 @@ static void inode_reclaim_dmap_range(struct fuse_conn *fc, struct inode *inode,
end);
if (!dmap)
break;
+ /* inode is going away. There should not be any users of dmap */
+ WARN_ON(refcount_read(&dmap->refcnt) > 1);
fuse_dax_interval_tree_remove(dmap, &fi->dmap_tree);
num++;
list_add(&dmap->list, &to_remove);
@@ -434,6 +473,21 @@ static void inode_reclaim_dmap_range(struct fuse_conn *fc, struct inode *inode,
spin_unlock(&fc->lock);
}

+static int dmap_removemapping_one(struct inode *inode,
+ struct fuse_dax_mapping *dmap)
+{
+ struct fuse_removemapping_one forget_one;
+ struct fuse_removemapping_in inarg;
+
+ memset(&inarg, 0, sizeof(inarg));
+ inarg.count = 1;
+ memset(&forget_one, 0, sizeof(forget_one));
+ forget_one.moffset = dmap->window_offset;
+ forget_one.len = dmap->length;
+
+ return fuse_send_removemapping(inode, &inarg, &forget_one);
+}
+
/*
* It is called from evict_inode() and by that time inode is going away. So
* this function does not take any locks like fi->i_dmap_sem for traversing
@@ -1903,6 +1957,17 @@ static void fuse_fill_iomap(struct inode *inode, loff_t pos, loff_t length,
if (flags & IOMAP_FAULT)
iomap->length = ALIGN(len, PAGE_SIZE);
iomap->type = IOMAP_MAPPED;
+ /*
+ * increace refcnt so that reclaim code knows this dmap is in
+ * use. This assumes i_dmap_sem mutex is held either
+ * shared/exclusive.
+ */
+ refcount_inc(&dmap->refcnt);
+
+ /* iomap->private should be NULL */
+ WARN_ON_ONCE(iomap->private);
+ iomap->private = dmap;
+
pr_debug("%s: returns iomap: addr 0x%llx offset 0x%llx"
" length 0x%llx\n", __func__, iomap->addr,
iomap->offset, iomap->length);
@@ -1925,8 +1990,12 @@ static int iomap_begin_setup_new_mapping(struct inode *inode, loff_t pos,
int ret;
bool writable = flags & IOMAP_WRITE;

- alloc_dmap = alloc_dax_mapping(fc);
- if (!alloc_dmap)
+ alloc_dmap = alloc_dax_mapping_reclaim(fc, inode, flags & IOMAP_FAULT);
+ if (IS_ERR(alloc_dmap))
+ return PTR_ERR(alloc_dmap);
+
+ /* If we are here, we should have memory allocated */
+ if (WARN_ON(!alloc_dmap))
return -EBUSY;

/*
@@ -1979,14 +2048,25 @@ static int iomap_begin_upgrade_mapping(struct inode *inode, loff_t pos,
dmap = fuse_dax_interval_tree_iter_first(&fi->dmap_tree, pos, pos);

/* We are holding either inode lock or i_mmap_sem, and that should
- * ensure that dmap can't reclaimed or truncated and it should still
- * be there in tree despite the fact we dropped and re-acquired the
- * lock.
+ * ensure that dmap can't be truncated. We are holding a reference
+ * on dmap and that should make sure it can't be reclaimed. So dmap
+ * should still be there in tree despite the fact we dropped and
+ * re-acquired the i_dmap_sem lock.
*/
ret = -EIO;
if (WARN_ON(!dmap))
goto out_err;

+ /* We took an extra reference on dmap to make sure its not reclaimd.
+ * Now we hold i_dmap_sem lock and that reference is not needed
+ * anymore. Drop it.
+ */
+ if (refcount_dec_and_test(&dmap->refcnt)) {
+ /* refcount should not hit 0. This object only goes
+ * away when fuse connection goes away */
+ WARN_ON_ONCE(1);
+ }
+
/* Maybe another thread already upgraded mapping while we were not
* holding lock.
*/
@@ -2056,7 +2136,11 @@ static int fuse_iomap_begin(struct inode *inode, loff_t pos, loff_t length,
* two threads to be trying to this simultaneously
* for same dmap. So drop shared lock and acquire
* exclusive lock.
+ *
+ * Before dropping i_dmap_sem lock, take reference
+ * on dmap so that its not freed by range reclaim.
*/
+ refcount_inc(&dmap->refcnt);
up_read(&fi->i_dmap_sem);
pr_debug("%s: Upgrading mapping at offset 0x%llx"
" length 0x%llx\n", __func__, pos, length);
@@ -2092,6 +2176,16 @@ static int fuse_iomap_end(struct inode *inode, loff_t pos, loff_t length,
ssize_t written, unsigned flags,
struct iomap *iomap)
{
+ struct fuse_dax_mapping *dmap = iomap->private;
+
+ if (dmap) {
+ if (refcount_dec_and_test(&dmap->refcnt)) {
+ /* refcount should not hit 0. This object only goes
+ * away when fuse connection goes away */
+ WARN_ON_ONCE(1);
+ }
+ }
+
/* DAX writes beyond end-of-file aren't handled using iomap, so the
* file size is unchanged and there is nothing to do here.
*/
@@ -4103,3 +4197,345 @@ void fuse_init_file_inode(struct inode *inode)
inode->i_data.a_ops = &fuse_dax_file_aops;
}
}
+
+static int dmap_writeback_invalidate(struct inode *inode,
+ struct fuse_dax_mapping *dmap)
+{
+ int ret;
+
+ ret = filemap_fdatawrite_range(inode->i_mapping, dmap->start,
+ dmap->end);
+ if (ret) {
+ printk("filemap_fdatawrite_range() failed. err=%d start=0x%llx,"
+ " end=0x%llx\n", ret, dmap->start, dmap->end);
+ return ret;
+ }
+
+ ret = invalidate_inode_pages2_range(inode->i_mapping,
+ dmap->start >> PAGE_SHIFT,
+ dmap->end >> PAGE_SHIFT);
+ if (ret)
+ printk("invalidate_inode_pages2_range() failed err=%d\n", ret);
+
+ return ret;
+}
+
+static int reclaim_one_dmap_locked(struct fuse_conn *fc, struct inode *inode,
+ struct fuse_dax_mapping *dmap)
+{
+ int ret;
+ struct fuse_inode *fi = get_fuse_inode(inode);
+
+ /*
+ * igrab() was done to make sure inode won't go under us, and this
+ * further avoids the race with evict().
+ */
+ ret = dmap_writeback_invalidate(inode, dmap);
+ if (ret)
+ return ret;
+
+ /* Remove dax mapping from inode interval tree now */
+ fuse_dax_interval_tree_remove(dmap, &fi->dmap_tree);
+ fi->nr_dmaps--;
+
+ /* It is possible that umount/shutodwn has killed the fuse connection
+ * and worker thread is trying to reclaim memory in parallel. So check
+ * if connection is still up or not otherwise don't send removemapping
+ * message.
+ */
+ if (fc->connected) {
+ ret = dmap_removemapping_one(inode, dmap);
+ if (ret) {
+ pr_warn("Failed to remove mapping. offset=0x%llx"
+ " len=0x%llx ret=%d\n", dmap->window_offset,
+ dmap->length, ret);
+ }
+ }
+ return 0;
+}
+
+static void fuse_wait_dax_page(struct inode *inode)
+{
+ struct fuse_inode *fi = get_fuse_inode(inode);
+
+ up_write(&fi->i_mmap_sem);
+ schedule();
+ down_write(&fi->i_mmap_sem);
+}
+
+/* Should be called with fi->i_mmap_sem lock held exclusively */
+static int __fuse_break_dax_layouts(struct inode *inode, bool *retry,
+ loff_t start, loff_t end)
+{
+ struct page *page;
+
+ page = dax_layout_busy_page_range(inode->i_mapping, start, end);
+ if (!page)
+ return 0;
+
+ *retry = true;
+ return ___wait_var_event(&page->_refcount,
+ atomic_read(&page->_refcount) == 1, TASK_INTERRUPTIBLE,
+ 0, 0, fuse_wait_dax_page(inode));
+}
+
+/* dmap_end == 0 leads to unmapping of whole file */
+static int fuse_break_dax_layouts(struct inode *inode, u64 dmap_start,
+ u64 dmap_end)
+{
+ bool retry;
+ int ret;
+
+ do {
+ retry = false;
+ ret = __fuse_break_dax_layouts(inode, &retry, dmap_start,
+ dmap_end);
+ } while (ret == 0 && retry);
+
+ return ret;
+}
+
+/* Find first mapping in the tree and free it. */
+static struct fuse_dax_mapping *
+inode_reclaim_one_dmap_locked(struct fuse_conn *fc, struct inode *inode)
+{
+ struct fuse_inode *fi = get_fuse_inode(inode);
+ struct fuse_dax_mapping *dmap;
+ int ret;
+
+ for (dmap = fuse_dax_interval_tree_iter_first(&fi->dmap_tree, 0, -1);
+ dmap;
+ dmap = fuse_dax_interval_tree_iter_next(dmap, 0, -1)) {
+ /* still in use. */
+ if (refcount_read(&dmap->refcnt) > 1)
+ continue;
+
+ ret = reclaim_one_dmap_locked(fc, inode, dmap);
+ if (ret < 0)
+ return ERR_PTR(ret);
+
+ /* Clean up dmap. Do not add back to free list */
+ dmap_remove_busy_list(fc, dmap);
+ dmap->inode = NULL;
+ dmap->start = dmap->end = 0;
+
+ pr_debug("fuse: %s: reclaimed memory range. inode=%px,"
+ " window_offset=0x%llx, length=0x%llx\n", __func__,
+ inode, dmap->window_offset, dmap->length);
+ return dmap;
+ }
+
+ return NULL;
+}
+
+/*
+ * Find first mapping in the tree and free it and return it. Do not add
+ * it back to free pool. If fault == true, this function should be called
+ * with fi->i_mmap_sem held.
+ */
+static struct fuse_dax_mapping *inode_reclaim_one_dmap(struct fuse_conn *fc,
+ struct inode *inode,
+ bool fault)
+{
+ struct fuse_inode *fi = get_fuse_inode(inode);
+ struct fuse_dax_mapping *dmap;
+ int ret;
+
+ if (!fault)
+ down_write(&fi->i_mmap_sem);
+
+ /*
+ * Make sure there are no references to inode pages using
+ * get_user_pages()
+ */
+ ret = fuse_break_dax_layouts(inode, 0, 0);
+ if (ret) {
+ printk("virtio_fs: fuse_break_dax_layouts() failed. err=%d\n",
+ ret);
+ dmap = ERR_PTR(ret);
+ goto out_mmap_sem;
+ }
+ down_write(&fi->i_dmap_sem);
+ dmap = inode_reclaim_one_dmap_locked(fc, inode);
+ up_write(&fi->i_dmap_sem);
+out_mmap_sem:
+ if (!fault)
+ up_write(&fi->i_mmap_sem);
+ return dmap;
+}
+
+/* If fault == true, it should be called with fi->i_mmap_sem locked */
+static struct fuse_dax_mapping *alloc_dax_mapping_reclaim(struct fuse_conn *fc,
+ struct inode *inode, bool fault)
+{
+ struct fuse_dax_mapping *dmap;
+ struct fuse_inode *fi = get_fuse_inode(inode);
+
+ while(1) {
+ dmap = alloc_dax_mapping(fc);
+ if (dmap)
+ return dmap;
+
+ if (fi->nr_dmaps) {
+ dmap = inode_reclaim_one_dmap(fc, inode, fault);
+ if (dmap)
+ return dmap;
+ /* If we could not reclaim a mapping because it
+ * had a reference, that should be a temporary
+ * situation. Try again.
+ */
+ msleep(1);
+ continue;
+ }
+ /*
+ * There are no mappings which can be reclaimed.
+ * Wait for one.
+ */
+ if (!(fc->nr_free_ranges > 0)) {
+ if (wait_event_killable_exclusive(fc->dax_range_waitq,
+ (fc->nr_free_ranges > 0)))
+ return ERR_PTR(-EINTR);
+ }
+ }
+}
+
+static int lookup_and_reclaim_dmap_locked(struct fuse_conn *fc,
+ struct inode *inode, u64 dmap_start)
+{
+ int ret;
+ struct fuse_inode *fi = get_fuse_inode(inode);
+ struct fuse_dax_mapping *dmap;
+
+ /* Find fuse dax mapping at file offset inode. */
+ dmap = fuse_dax_interval_tree_iter_first(&fi->dmap_tree, dmap_start,
+ dmap_start);
+
+ /* Range already got cleaned up by somebody else */
+ if (!dmap)
+ return 0;
+
+ /* still in use. */
+ if (refcount_read(&dmap->refcnt) > 1)
+ return 0;
+
+ ret = reclaim_one_dmap_locked(fc, inode, dmap);
+ if (ret < 0)
+ return ret;
+
+ /* Cleanup dmap entry and add back to free list */
+ spin_lock(&fc->lock);
+ dmap_reinit_add_to_free_pool(fc, dmap);
+ spin_unlock(&fc->lock);
+ return ret;
+}
+
+/*
+ * Free a range of memory.
+ * Locking.
+ * 1. Take fuse_inode->i_mmap_sem to block dax faults.
+ * 2. Take fuse_inode->i_dmap_sem to protect interval tree and also to make
+ * sure read/write can not reuse a dmap which we might be freeing.
+ */
+static int lookup_and_reclaim_dmap(struct fuse_conn *fc, struct inode *inode,
+ u64 dmap_start, u64 dmap_end)
+{
+ int ret;
+ struct fuse_inode *fi = get_fuse_inode(inode);
+
+ down_write(&fi->i_mmap_sem);
+ ret = fuse_break_dax_layouts(inode, dmap_start, dmap_end);
+ if (ret) {
+ printk("virtio_fs: fuse_break_dax_layouts() failed. err=%d\n",
+ ret);
+ goto out_mmap_sem;
+ }
+
+ down_write(&fi->i_dmap_sem);
+ ret = lookup_and_reclaim_dmap_locked(fc, inode, dmap_start);
+ up_write(&fi->i_dmap_sem);
+out_mmap_sem:
+ up_write(&fi->i_mmap_sem);
+ return ret;
+}
+
+static int try_to_free_dmap_chunks(struct fuse_conn *fc,
+ unsigned long nr_to_free)
+{
+ struct fuse_dax_mapping *dmap, *pos, *temp;
+ int ret, nr_freed = 0;
+ u64 dmap_start = 0, window_offset = 0, dmap_end = 0;
+ struct inode *inode = NULL;
+
+ /* Pick first busy range and free it for now*/
+ while(1) {
+ if (nr_freed >= nr_to_free)
+ break;
+
+ dmap = NULL;
+ spin_lock(&fc->lock);
+
+ if (!fc->nr_busy_ranges) {
+ spin_unlock(&fc->lock);
+ return 0;
+ }
+
+ list_for_each_entry_safe(pos, temp, &fc->busy_ranges,
+ busy_list) {
+ /* skip this range if it's in use. */
+ if (refcount_read(&pos->refcnt) > 1)
+ continue;
+
+ inode = igrab(pos->inode);
+ /*
+ * This inode is going away. That will free
+ * up all the ranges anyway, continue to
+ * next range.
+ */
+ if (!inode)
+ continue;
+ /*
+ * Take this element off list and add it tail. If
+ * this element can't be freed, it will help with
+ * selecting new element in next iteration of loop.
+ */
+ dmap = pos;
+ list_move_tail(&dmap->busy_list, &fc->busy_ranges);
+ dmap_start = dmap->start;
+ dmap_end = dmap->end;
+ window_offset = dmap->window_offset;
+ break;
+ }
+ spin_unlock(&fc->lock);
+ if (!dmap)
+ return 0;
+
+ ret = lookup_and_reclaim_dmap(fc, inode, dmap_start, dmap_end);
+ iput(inode);
+ if (ret) {
+ printk("%s(window_offset=0x%llx) failed. err=%d\n",
+ __func__, window_offset, ret);
+ return ret;
+ }
+ nr_freed++;
+ }
+ return 0;
+}
+
+void fuse_dax_free_mem_worker(struct work_struct *work)
+{
+ int ret;
+ struct fuse_conn *fc = container_of(work, struct fuse_conn,
+ dax_free_work.work);
+ pr_debug("fuse: Worker to free memory called. nr_free_ranges=%lu"
+ " nr_busy_ranges=%lu\n", fc->nr_free_ranges,
+ fc->nr_busy_ranges);
+
+ ret = try_to_free_dmap_chunks(fc, FUSE_DAX_RECLAIM_CHUNK);
+ if (ret) {
+ pr_debug("fuse: try_to_free_dmap_chunks() failed with err=%d\n",
+ ret);
+ }
+
+ /* If number of free ranges are still below threhold, requeue */
+ kick_dmap_free_worker(fc, 1);
+}
diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index de213a7e1b0e..41c2fbff0d37 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -54,6 +54,16 @@
#define FUSE_DAX_MEM_RANGE_SZ (2*1024*1024)
#define FUSE_DAX_MEM_RANGE_PAGES (FUSE_DAX_MEM_RANGE_SZ/PAGE_SIZE)

+/* Number of ranges reclaimer will try to free in one invocation */
+#define FUSE_DAX_RECLAIM_CHUNK (10)
+
+/*
+ * Dax memory reclaim threshold in percetage of total ranges. When free
+ * number of free ranges drops below this threshold, reclaim can trigger
+ * Default is 20%
+ * */
+#define FUSE_DAX_RECLAIM_THRESHOLD (20)
+
/** List of active connections */
extern struct list_head fuse_conn_list;

@@ -75,6 +85,9 @@ struct fuse_forget_link {

/** Translation information for file offsets to DAX window offsets */
struct fuse_dax_mapping {
+ /* Pointer to inode where this memory range is mapped */
+ struct inode *inode;
+
/* Will connect in fc->free_ranges to keep track of free memory */
struct list_head list;

@@ -97,6 +110,9 @@ struct fuse_dax_mapping {

/* Is this mapping read-only or read-write */
bool writable;
+
+ /* reference count when the mapping is used by dax iomap. */
+ refcount_t refcnt;
};

/** FUSE inode */
@@ -822,11 +838,19 @@ struct fuse_conn {
unsigned long nr_busy_ranges;
struct list_head busy_ranges;

+ /* Worker to free up memory ranges */
+ struct delayed_work dax_free_work;
+
+ /* Wait queue for a dax range to become free */
+ wait_queue_head_t dax_range_waitq;
+
/*
* DAX Window Free Ranges
*/
long nr_free_ranges;
struct list_head free_ranges;
+
+ unsigned long nr_ranges;
};

static inline struct fuse_conn *get_fuse_conn_super(struct super_block *sb)
@@ -1164,6 +1188,7 @@ unsigned int fuse_len_args(unsigned int numargs, struct fuse_arg *args);
*/
u64 fuse_get_unique(struct fuse_iqueue *fiq);
void fuse_free_conn(struct fuse_conn *fc);
+void fuse_dax_free_mem_worker(struct work_struct *work);
void fuse_cleanup_inode_mappings(struct inode *inode);

#endif /* _FS_FUSE_I_H */
diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
index d4770e7fb7eb..3560b62077a7 100644
--- a/fs/fuse/inode.c
+++ b/fs/fuse/inode.c
@@ -663,11 +663,13 @@ static int fuse_dax_mem_range_init(struct fuse_conn *fc,
range->window_offset = i * FUSE_DAX_MEM_RANGE_SZ;
range->length = FUSE_DAX_MEM_RANGE_SZ;
INIT_LIST_HEAD(&range->busy_list);
+ refcount_set(&range->refcnt, 1);
list_add_tail(&range->list, &mem_ranges);
}

list_replace_init(&mem_ranges, &fc->free_ranges);
fc->nr_free_ranges = nr_ranges;
+ fc->nr_ranges = nr_ranges;
return 0;
out_err:
/* Free All allocated elements */
@@ -692,6 +694,7 @@ void fuse_conn_init(struct fuse_conn *fc, struct user_namespace *user_ns,
refcount_set(&fc->count, 1);
atomic_set(&fc->dev_count, 1);
init_waitqueue_head(&fc->blocked_waitq);
+ init_waitqueue_head(&fc->dax_range_waitq);
fuse_iqueue_init(&fc->iq, fiq_ops, fiq_priv);
INIT_LIST_HEAD(&fc->bg_queue);
INIT_LIST_HEAD(&fc->entry);
@@ -711,6 +714,7 @@ void fuse_conn_init(struct fuse_conn *fc, struct user_namespace *user_ns,
fc->max_pages = FUSE_DEFAULT_MAX_PAGES_PER_REQ;
INIT_LIST_HEAD(&fc->free_ranges);
INIT_LIST_HEAD(&fc->busy_ranges);
+ INIT_DELAYED_WORK(&fc->dax_free_work, fuse_dax_free_mem_worker);
}
EXPORT_SYMBOL_GPL(fuse_conn_init);

@@ -719,6 +723,7 @@ void fuse_conn_put(struct fuse_conn *fc)
if (refcount_dec_and_test(&fc->count)) {
struct fuse_iqueue *fiq = &fc->iq;

+ flush_delayed_work(&fc->dax_free_work);
if (fc->dax_dev)
fuse_free_dax_mem_ranges(&fc->free_ranges);
if (fiq->ops->release)
--
2.20.1
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