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Subject[PATCH 35/52] fuse: Add logic to do direct reclaim of memory
Date
This can be done only from same inode. Also it can be done only for
read/write case and not for fault case. Reason, as of now reclaim requires
holding inode_lock, fuse_inode->i_mmap_sem and fuse_inode->dmap_tree
locks in that order and only read/write path will allow that (and not
fault path).

Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
---
fs/fuse/file.c | 121 +++++++++++++++++++++++++++++++++++++++++++++++++--------
1 file changed, 105 insertions(+), 16 deletions(-)

diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index 17becdff3014..13db83d105ff 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -30,6 +30,8 @@ INTERVAL_TREE_DEFINE(struct fuse_dax_mapping,

static long __fuse_file_fallocate(struct file *file, int mode,
loff_t offset, loff_t length);
+static struct fuse_dax_mapping *alloc_dax_mapping_reclaim(struct fuse_conn *fc,
+ struct inode *inode);

static int fuse_send_open(struct fuse_conn *fc, u64 nodeid, struct file *file,
int opcode, struct fuse_open_out *outargp)
@@ -1727,7 +1729,12 @@ static int fuse_iomap_begin(struct inode *inode, loff_t pos, loff_t length,
if (pos >= i_size_read(inode))
goto iomap_hole;

- alloc_dmap = alloc_dax_mapping(fc);
+ /* Can't do reclaim in fault path yet due to lock ordering */
+ if (flags & IOMAP_FAULT)
+ alloc_dmap = alloc_dax_mapping(fc);
+ else
+ alloc_dmap = alloc_dax_mapping_reclaim(fc, inode);
+
if (!alloc_dmap)
return -EBUSY;

@@ -3705,24 +3712,14 @@ void fuse_init_file_inode(struct inode *inode)
}
}

-int fuse_dax_free_one_mapping_locked(struct fuse_conn *fc, struct inode *inode,
- u64 dmap_start)
+int fuse_dax_reclaim_dmap_locked(struct fuse_conn *fc, struct inode *inode,
+ struct fuse_dax_mapping *dmap)
{
int ret;
struct fuse_inode *fi = get_fuse_inode(inode);
- struct fuse_dax_mapping *dmap;
-
- WARN_ON(!inode_is_locked(inode));
-
- /* 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;

- ret = filemap_fdatawrite_range(inode->i_mapping, dmap->start, dmap->end);
+ 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);
@@ -3743,6 +3740,99 @@ int fuse_dax_free_one_mapping_locked(struct fuse_conn *fc, struct inode *inode,
/* Remove dax mapping from inode interval tree now */
fuse_dax_interval_tree_remove(dmap, &fi->dmap_tree);
fi->nr_dmaps--;
+ return 0;
+}
+
+/* First first mapping in the tree and free it. */
+struct fuse_dax_mapping *fuse_dax_reclaim_first_mapping_locked(
+ struct fuse_conn *fc, struct inode *inode)
+{
+ struct fuse_inode *fi = get_fuse_inode(inode);
+ struct fuse_dax_mapping *dmap;
+ int ret;
+
+ /* Find fuse dax mapping at file offset inode. */
+ dmap = fuse_dax_interval_tree_iter_first(&fi->dmap_tree, 0, -1);
+ if (!dmap)
+ return NULL;
+
+ ret = fuse_dax_reclaim_dmap_locked(fc, inode, dmap);
+ if (ret < 0)
+ return ERR_PTR(ret);
+
+ /* Clean up dmap. Do not add back to free list */
+ spin_lock(&fc->lock);
+ list_del_init(&dmap->busy_list);
+ WARN_ON(fc->nr_busy_ranges == 0);
+ fc->nr_busy_ranges--;
+ dmap->inode = NULL;
+ dmap->start = dmap->end = 0;
+ spin_unlock(&fc->lock);
+
+ pr_debug("fuse: reclaimed memory range window_offset=0x%llx,"
+ " length=0x%llx\n", dmap->window_offset,
+ dmap->length);
+ return dmap;
+}
+
+/*
+ * First first mapping in the tree and free it and return it. Do not add
+ * it back to free pool.
+ *
+ * This is called with inode lock held.
+ */
+struct fuse_dax_mapping *fuse_dax_reclaim_first_mapping(struct fuse_conn *fc,
+ struct inode *inode)
+{
+ struct fuse_inode *fi = get_fuse_inode(inode);
+ struct fuse_dax_mapping *dmap;
+
+ down_write(&fi->i_mmap_sem);
+ down_write(&fi->i_dmap_sem);
+ dmap = fuse_dax_reclaim_first_mapping_locked(fc, inode);
+ up_write(&fi->i_dmap_sem);
+ up_write(&fi->i_mmap_sem);
+ return dmap;
+}
+
+static struct fuse_dax_mapping *alloc_dax_mapping_reclaim(struct fuse_conn *fc,
+ struct inode *inode)
+{
+ struct fuse_dax_mapping *dmap;
+ struct fuse_inode *fi = get_fuse_inode(inode);
+
+ dmap = alloc_dax_mapping(fc);
+ if (dmap)
+ return dmap;
+
+ /* There are no mappings which can be reclaimed */
+ if (!fi->nr_dmaps)
+ return NULL;
+
+ /* Try reclaim a fuse dax memory range */
+ return fuse_dax_reclaim_first_mapping(fc, inode);
+}
+
+int fuse_dax_free_one_mapping_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;
+
+ WARN_ON(!inode_is_locked(inode));
+
+ /* 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;
+
+ ret = fuse_dax_reclaim_dmap_locked(fc, inode, dmap);
+ if (ret < 0)
+ return ret;

/* Cleanup dmap entry and add back to free list */
spin_lock(&fc->lock);
@@ -3757,7 +3847,6 @@ int fuse_dax_free_one_mapping_locked(struct fuse_conn *fc, struct inode *inode,
pr_debug("fuse: freed memory range window_offset=0x%llx,"
" length=0x%llx\n", dmap->window_offset,
dmap->length);
-
return ret;
}

--
2.13.6
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