#include "fuse_i.h"
+#include <linux/delay.h>
#include <linux/dax.h>
+#include <linux/uio.h>
#include <linux/pfn_t.h>
+#include <linux/iomap.h>
+#include <linux/interval_tree.h>
-/* Default memory range size, 2MB */
+/*
+ * Default memory range size. A power of 2 so it agrees with common FUSE_INIT
+ * map_alignment values 4KB and 64KB.
+ */
#define FUSE_DAX_SHIFT 21
#define FUSE_DAX_SZ (1 << FUSE_DAX_SHIFT)
#define FUSE_DAX_PAGES (FUSE_DAX_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)
+
/** 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 fcd->free_ranges to keep track of free memory */
struct list_head list;
+ /* For interval tree in file/inode */
+ struct interval_tree_node itn;
+
+ /* Will connect in fc->busy_ranges to keep track busy memory */
+ struct list_head busy_list;
+
/** Position in DAX window */
u64 window_offset;
/** Length of mapping, in bytes */
loff_t length;
+
+ /* Is this mapping read-only or read-write */
+ bool writable;
+
+ /* reference count when the mapping is used by dax iomap. */
+ refcount_t refcnt;
+};
+
+/* Per-inode dax map */
+struct fuse_inode_dax {
+ /* Semaphore to protect modifications to the dmap tree */
+ struct rw_semaphore sem;
+
+ /* Sorted rb tree of struct fuse_dax_mapping elements */
+ struct rb_root_cached tree;
+ unsigned long nr;
};
struct fuse_conn_dax {
/* DAX device */
struct dax_device *dev;
+ /* Lock protecting accessess to members of this structure */
+ spinlock_t lock;
+
+ /* List of memory ranges which are busy */
+ unsigned long nr_busy_ranges;
+ struct list_head busy_ranges;
+
+ /* Worker to free up memory ranges */
+ struct delayed_work free_work;
+
+ /* Wait queue for a dax range to become free */
+ wait_queue_head_t range_waitq;
+
/* DAX Window Free Ranges */
long nr_free_ranges;
struct list_head free_ranges;
+
+ unsigned long nr_ranges;
};
+static inline struct fuse_dax_mapping *
+node_to_dmap(struct interval_tree_node *node)
+{
+ if (!node)
+ return NULL;
+
+ return container_of(node, struct fuse_dax_mapping, itn);
+}
+
+static struct fuse_dax_mapping *
+alloc_dax_mapping_reclaim(struct fuse_conn_dax *fcd, struct inode *inode);
+
+static void
+__kick_dmap_free_worker(struct fuse_conn_dax *fcd, unsigned long delay_ms)
+{
+ unsigned long free_threshold;
+
+ /* If number of free ranges are below threshold, start reclaim */
+ free_threshold = max_t(unsigned long, fcd->nr_ranges * FUSE_DAX_RECLAIM_THRESHOLD / 100,
+ 1);
+ if (fcd->nr_free_ranges < free_threshold)
+ queue_delayed_work(system_long_wq, &fcd->free_work,
+ msecs_to_jiffies(delay_ms));
+}
+
+static void kick_dmap_free_worker(struct fuse_conn_dax *fcd,
+ unsigned long delay_ms)
+{
+ spin_lock(&fcd->lock);
+ __kick_dmap_free_worker(fcd, delay_ms);
+ spin_unlock(&fcd->lock);
+}
+
+static struct fuse_dax_mapping *alloc_dax_mapping(struct fuse_conn_dax *fcd)
+{
+ struct fuse_dax_mapping *dmap;
+
+ spin_lock(&fcd->lock);
+ dmap = list_first_entry_or_null(&fcd->free_ranges,
+ struct fuse_dax_mapping, list);
+ if (dmap) {
+ list_del_init(&dmap->list);
+ WARN_ON(fcd->nr_free_ranges <= 0);
+ fcd->nr_free_ranges--;
+ }
+ spin_unlock(&fcd->lock);
+
+ kick_dmap_free_worker(fcd, 0);
+ return dmap;
+}
+
+/* This assumes fcd->lock is held */
+static void __dmap_remove_busy_list(struct fuse_conn_dax *fcd,
+ struct fuse_dax_mapping *dmap)
+{
+ list_del_init(&dmap->busy_list);
+ WARN_ON(fcd->nr_busy_ranges == 0);
+ fcd->nr_busy_ranges--;
+}
+
+static void dmap_remove_busy_list(struct fuse_conn_dax *fcd,
+ struct fuse_dax_mapping *dmap)
+{
+ spin_lock(&fcd->lock);
+ __dmap_remove_busy_list(fcd, dmap);
+ spin_unlock(&fcd->lock);
+}
+
+/* This assumes fcd->lock is held */
+static void __dmap_add_to_free_pool(struct fuse_conn_dax *fcd,
+ struct fuse_dax_mapping *dmap)
+{
+ list_add_tail(&dmap->list, &fcd->free_ranges);
+ fcd->nr_free_ranges++;
+ wake_up(&fcd->range_waitq);
+}
+
+static void dmap_add_to_free_pool(struct fuse_conn_dax *fcd,
+ struct fuse_dax_mapping *dmap)
+{
+ /* Return fuse_dax_mapping to free list */
+ spin_lock(&fcd->lock);
+ __dmap_add_to_free_pool(fcd, dmap);
+ spin_unlock(&fcd->lock);
+}
+
+static int fuse_setup_one_mapping(struct inode *inode, unsigned long start_idx,
+ struct fuse_dax_mapping *dmap, bool writable,
+ bool upgrade)
+{
+ struct fuse_mount *fm = get_fuse_mount(inode);
+ struct fuse_conn_dax *fcd = fm->fc->dax;
+ struct fuse_inode *fi = get_fuse_inode(inode);
+ struct fuse_setupmapping_in inarg;
+ loff_t offset = start_idx << FUSE_DAX_SHIFT;
+ FUSE_ARGS(args);
+ ssize_t err;
+
+ WARN_ON(fcd->nr_free_ranges < 0);
+
+ /* Ask fuse daemon to setup mapping */
+ memset(&inarg, 0, sizeof(inarg));
+ inarg.foffset = offset;
+ inarg.fh = -1;
+ inarg.moffset = dmap->window_offset;
+ inarg.len = FUSE_DAX_SZ;
+ inarg.flags |= FUSE_SETUPMAPPING_FLAG_READ;
+ if (writable)
+ inarg.flags |= FUSE_SETUPMAPPING_FLAG_WRITE;
+ args.opcode = FUSE_SETUPMAPPING;
+ args.nodeid = fi->nodeid;
+ args.in_numargs = 1;
+ args.in_args[0].size = sizeof(inarg);
+ args.in_args[0].value = &inarg;
+ err = fuse_simple_request(fm, &args);
+ if (err < 0)
+ return err;
+ 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->itn.start = dmap->itn.last = start_idx;
+ /* Protected by fi->dax->sem */
+ interval_tree_insert(&dmap->itn, &fi->dax->tree);
+ fi->dax->nr++;
+ spin_lock(&fcd->lock);
+ list_add_tail(&dmap->busy_list, &fcd->busy_ranges);
+ fcd->nr_busy_ranges++;
+ spin_unlock(&fcd->lock);
+ }
+ return 0;
+}
+
+static int fuse_send_removemapping(struct inode *inode,
+ struct fuse_removemapping_in *inargp,
+ struct fuse_removemapping_one *remove_one)
+{
+ struct fuse_inode *fi = get_fuse_inode(inode);
+ struct fuse_mount *fm = get_fuse_mount(inode);
+ FUSE_ARGS(args);
+
+ args.opcode = FUSE_REMOVEMAPPING;
+ args.nodeid = fi->nodeid;
+ args.in_numargs = 2;
+ args.in_args[0].size = sizeof(*inargp);
+ args.in_args[0].value = inargp;
+ args.in_args[1].size = inargp->count * sizeof(*remove_one);
+ args.in_args[1].value = remove_one;
+ return fuse_simple_request(fm, &args);
+}
+
+static int dmap_removemapping_list(struct inode *inode, unsigned int num,
+ struct list_head *to_remove)
+{
+ struct fuse_removemapping_one *remove_one, *ptr;
+ struct fuse_removemapping_in inarg;
+ struct fuse_dax_mapping *dmap;
+ int ret, i = 0, nr_alloc;
+
+ nr_alloc = min_t(unsigned int, num, FUSE_REMOVEMAPPING_MAX_ENTRY);
+ remove_one = kmalloc_array(nr_alloc, sizeof(*remove_one), GFP_NOFS);
+ if (!remove_one)
+ return -ENOMEM;
+
+ ptr = remove_one;
+ list_for_each_entry(dmap, to_remove, list) {
+ ptr->moffset = dmap->window_offset;
+ ptr->len = dmap->length;
+ ptr++;
+ i++;
+ num--;
+ if (i >= nr_alloc || num == 0) {
+ memset(&inarg, 0, sizeof(inarg));
+ inarg.count = i;
+ ret = fuse_send_removemapping(inode, &inarg,
+ remove_one);
+ if (ret)
+ goto out;
+ ptr = remove_one;
+ i = 0;
+ }
+ }
+out:
+ kfree(remove_one);
+ return ret;
+}
+
+/*
+ * Cleanup dmap entry and add back to free list. This should be called with
+ * fcd->lock held.
+ */
+static void dmap_reinit_add_to_free_pool(struct fuse_conn_dax *fcd,
+ struct fuse_dax_mapping *dmap)
+{
+ pr_debug("fuse: freeing memory range start_idx=0x%lx end_idx=0x%lx window_offset=0x%llx length=0x%llx\n",
+ dmap->itn.start, dmap->itn.last, dmap->window_offset,
+ dmap->length);
+ __dmap_remove_busy_list(fcd, dmap);
+ dmap->inode = NULL;
+ dmap->itn.start = dmap->itn.last = 0;
+ __dmap_add_to_free_pool(fcd, dmap);
+}
+
+/*
+ * Free inode dmap entries whose range falls inside [start, end].
+ * Does not take any locks. At this point of time it should only be
+ * called from evict_inode() path where we know all dmap entries can be
+ * reclaimed.
+ */
+static void inode_reclaim_dmap_range(struct fuse_conn_dax *fcd,
+ struct inode *inode,
+ loff_t start, loff_t end)
+{
+ struct fuse_inode *fi = get_fuse_inode(inode);
+ struct fuse_dax_mapping *dmap, *n;
+ int err, num = 0;
+ LIST_HEAD(to_remove);
+ unsigned long start_idx = start >> FUSE_DAX_SHIFT;
+ unsigned long end_idx = end >> FUSE_DAX_SHIFT;
+ struct interval_tree_node *node;
+
+ while (1) {
+ node = interval_tree_iter_first(&fi->dax->tree, start_idx,
+ end_idx);
+ if (!node)
+ break;
+ dmap = node_to_dmap(node);
+ /* inode is going away. There should not be any users of dmap */
+ WARN_ON(refcount_read(&dmap->refcnt) > 1);
+ interval_tree_remove(&dmap->itn, &fi->dax->tree);
+ num++;
+ list_add(&dmap->list, &to_remove);
+ }
+
+ /* Nothing to remove */
+ if (list_empty(&to_remove))
+ return;
+
+ WARN_ON(fi->dax->nr < num);
+ fi->dax->nr -= num;
+ err = dmap_removemapping_list(inode, num, &to_remove);
+ if (err && err != -ENOTCONN) {
+ pr_warn("Failed to removemappings. start=0x%llx end=0x%llx\n",
+ start, end);
+ }
+ spin_lock(&fcd->lock);
+ list_for_each_entry_safe(dmap, n, &to_remove, list) {
+ list_del_init(&dmap->list);
+ dmap_reinit_add_to_free_pool(fcd, dmap);
+ }
+ spin_unlock(&fcd->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->dax->sem for traversing
+ * that fuse inode interval tree. If that lock is taken then lock validator
+ * complains of deadlock situation w.r.t fs_reclaim lock.
+ */
+void fuse_dax_inode_cleanup(struct inode *inode)
+{
+ struct fuse_conn *fc = get_fuse_conn(inode);
+ struct fuse_inode *fi = get_fuse_inode(inode);
+
+ /*
+ * fuse_evict_inode() has already called truncate_inode_pages_final()
+ * before we arrive here. So we should not have to worry about any
+ * pages/exception entries still associated with inode.
+ */
+ inode_reclaim_dmap_range(fc->dax, inode, 0, -1);
+ WARN_ON(fi->dax->nr);
+}
+
+static void fuse_fill_iomap_hole(struct iomap *iomap, loff_t length)
+{
+ iomap->addr = IOMAP_NULL_ADDR;
+ iomap->length = length;
+ iomap->type = IOMAP_HOLE;
+}
+
+static void fuse_fill_iomap(struct inode *inode, loff_t pos, loff_t length,
+ struct iomap *iomap, struct fuse_dax_mapping *dmap,
+ unsigned int flags)
+{
+ loff_t offset, len;
+ loff_t i_size = i_size_read(inode);
+
+ offset = pos - (dmap->itn.start << FUSE_DAX_SHIFT);
+ len = min(length, dmap->length - offset);
+
+ /* If length is beyond end of file, truncate further */
+ if (pos + len > i_size)
+ len = i_size - pos;
+
+ if (len > 0) {
+ iomap->addr = dmap->window_offset + offset;
+ iomap->length = len;
+ 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 fi->dax->sem mutex is held either
+ * shared/exclusive.
+ */
+ refcount_inc(&dmap->refcnt);
+
+ /* iomap->private should be NULL */
+ WARN_ON_ONCE(iomap->private);
+ iomap->private = dmap;
+ } else {
+ /* Mapping beyond end of file is hole */
+ fuse_fill_iomap_hole(iomap, length);
+ }
+}
+
+static int fuse_setup_new_dax_mapping(struct inode *inode, loff_t pos,
+ loff_t length, unsigned int flags,
+ struct iomap *iomap)
+{
+ struct fuse_inode *fi = get_fuse_inode(inode);
+ struct fuse_conn *fc = get_fuse_conn(inode);
+ struct fuse_conn_dax *fcd = fc->dax;
+ struct fuse_dax_mapping *dmap, *alloc_dmap = NULL;
+ int ret;
+ bool writable = flags & IOMAP_WRITE;
+ unsigned long start_idx = pos >> FUSE_DAX_SHIFT;
+ struct interval_tree_node *node;
+
+ /*
+ * Can't do inline reclaim in fault path. We call
+ * dax_layout_busy_page() before we free a range. And
+ * fuse_wait_dax_page() drops fi->i_mmap_sem lock and requires it.
+ * In fault path we enter with fi->i_mmap_sem held and can't drop
+ * it. Also in fault path we hold fi->i_mmap_sem shared and not
+ * exclusive, so that creates further issues with fuse_wait_dax_page().
+ * Hence return -EAGAIN and fuse_dax_fault() will wait for a memory
+ * range to become free and retry.
+ */
+ if (flags & IOMAP_FAULT) {
+ alloc_dmap = alloc_dax_mapping(fcd);
+ if (!alloc_dmap)
+ return -EAGAIN;
+ } else {
+ alloc_dmap = alloc_dax_mapping_reclaim(fcd, inode);
+ 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 -EIO;
+
+ /*
+ * Take write lock so that only one caller can try to setup mapping
+ * and other waits.
+ */
+ down_write(&fi->dax->sem);
+ /*
+ * We dropped lock. Check again if somebody else setup
+ * mapping already.
+ */
+ node = interval_tree_iter_first(&fi->dax->tree, start_idx, start_idx);
+ if (node) {
+ dmap = node_to_dmap(node);
+ fuse_fill_iomap(inode, pos, length, iomap, dmap, flags);
+ dmap_add_to_free_pool(fcd, alloc_dmap);
+ up_write(&fi->dax->sem);
+ return 0;
+ }
+
+ /* Setup one mapping */
+ ret = fuse_setup_one_mapping(inode, pos >> FUSE_DAX_SHIFT, alloc_dmap,
+ writable, false);
+ if (ret < 0) {
+ dmap_add_to_free_pool(fcd, alloc_dmap);
+ up_write(&fi->dax->sem);
+ return ret;
+ }
+ fuse_fill_iomap(inode, pos, length, iomap, alloc_dmap, flags);
+ up_write(&fi->dax->sem);
+ return 0;
+}
+
+static int fuse_upgrade_dax_mapping(struct inode *inode, loff_t pos,
+ loff_t length, unsigned int flags,
+ struct iomap *iomap)
+{
+ struct fuse_inode *fi = get_fuse_inode(inode);
+ struct fuse_dax_mapping *dmap;
+ int ret;
+ unsigned long idx = pos >> FUSE_DAX_SHIFT;
+ struct interval_tree_node *node;
+
+ /*
+ * Take exclusive lock so that only one caller can try to setup
+ * mapping and others wait.
+ */
+ down_write(&fi->dax->sem);
+ node = interval_tree_iter_first(&fi->dax->tree, idx, idx);
+
+ /* We are holding either inode lock or i_mmap_sem, and that should
+ * 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 fi->dax->sem lock.
+ */
+ ret = -EIO;
+ if (WARN_ON(!node))
+ goto out_err;
+
+ dmap = node_to_dmap(node);
+
+ /* We took an extra reference on dmap to make sure its not reclaimd.
+ * Now we hold fi->dax->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.
+ */
+ if (dmap->writable) {
+ ret = 0;
+ goto out_fill_iomap;
+ }
+
+ ret = fuse_setup_one_mapping(inode, pos >> FUSE_DAX_SHIFT, dmap, true,
+ true);
+ if (ret < 0)
+ goto out_err;
+out_fill_iomap:
+ fuse_fill_iomap(inode, pos, length, iomap, dmap, flags);
+out_err:
+ up_write(&fi->dax->sem);
+ return ret;
+}
+
+/* This is just for DAX and the mapping is ephemeral, do not use it for other
+ * purposes since there is no block device with a permanent mapping.
+ */
+static int fuse_iomap_begin(struct inode *inode, loff_t pos, loff_t length,
+ unsigned int flags, struct iomap *iomap,
+ struct iomap *srcmap)
+{
+ struct fuse_inode *fi = get_fuse_inode(inode);
+ struct fuse_conn *fc = get_fuse_conn(inode);
+ struct fuse_dax_mapping *dmap;
+ bool writable = flags & IOMAP_WRITE;
+ unsigned long start_idx = pos >> FUSE_DAX_SHIFT;
+ struct interval_tree_node *node;
+
+ /* We don't support FIEMAP */
+ if (WARN_ON(flags & IOMAP_REPORT))
+ return -EIO;
+
+ iomap->offset = pos;
+ iomap->flags = 0;
+ iomap->bdev = NULL;
+ iomap->dax_dev = fc->dax->dev;
+
+ /*
+ * Both read/write and mmap path can race here. So we need something
+ * to make sure if we are setting up mapping, then other path waits
+ *
+ * For now, use a semaphore for this. It probably needs to be
+ * optimized later.
+ */
+ down_read(&fi->dax->sem);
+ node = interval_tree_iter_first(&fi->dax->tree, start_idx, start_idx);
+ if (node) {
+ dmap = node_to_dmap(node);
+ if (writable && !dmap->writable) {
+ /* Upgrade read-only mapping to read-write. This will
+ * require exclusive fi->dax->sem lock as we don't want
+ * two threads to be trying to this simultaneously
+ * for same dmap. So drop shared lock and acquire
+ * exclusive lock.
+ *
+ * Before dropping fi->dax->sem lock, take reference
+ * on dmap so that its not freed by range reclaim.
+ */
+ refcount_inc(&dmap->refcnt);
+ up_read(&fi->dax->sem);
+ pr_debug("%s: Upgrading mapping at offset 0x%llx length 0x%llx\n",
+ __func__, pos, length);
+ return fuse_upgrade_dax_mapping(inode, pos, length,
+ flags, iomap);
+ } else {
+ fuse_fill_iomap(inode, pos, length, iomap, dmap, flags);
+ up_read(&fi->dax->sem);
+ return 0;
+ }
+ } else {
+ up_read(&fi->dax->sem);
+ pr_debug("%s: no mapping at offset 0x%llx length 0x%llx\n",
+ __func__, pos, length);
+ if (pos >= i_size_read(inode))
+ goto iomap_hole;
+
+ return fuse_setup_new_dax_mapping(inode, pos, length, flags,
+ iomap);
+ }
+
+ /*
+ * If read beyond end of file happnes, fs code seems to return
+ * it as hole
+ */
+iomap_hole:
+ fuse_fill_iomap_hole(iomap, length);
+ pr_debug("%s returning hole mapping. pos=0x%llx length_asked=0x%llx length_returned=0x%llx\n",
+ __func__, pos, length, iomap->length);
+ return 0;
+}
+
+static int fuse_iomap_end(struct inode *inode, loff_t pos, loff_t length,
+ ssize_t written, unsigned int 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.
+ */
+ return 0;
+}
+
+static const struct iomap_ops fuse_iomap_ops = {
+ .iomap_begin = fuse_iomap_begin,
+ .iomap_end = fuse_iomap_end,
+};
+
+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_dax_break_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 */
+int fuse_dax_break_layouts(struct inode *inode, u64 dmap_start,
+ u64 dmap_end)
+{
+ bool retry;
+ int ret;
+
+ do {
+ retry = false;
+ ret = __fuse_dax_break_layouts(inode, &retry, dmap_start,
+ dmap_end);
+ } while (ret == 0 && retry);
+
+ return ret;
+}
+
+ssize_t fuse_dax_read_iter(struct kiocb *iocb, struct iov_iter *to)
+{
+ struct inode *inode = file_inode(iocb->ki_filp);
+ ssize_t ret;
+
+ if (iocb->ki_flags & IOCB_NOWAIT) {
+ if (!inode_trylock_shared(inode))
+ return -EAGAIN;
+ } else {
+ inode_lock_shared(inode);
+ }
+
+ ret = dax_iomap_rw(iocb, to, &fuse_iomap_ops);
+ inode_unlock_shared(inode);
+
+ /* TODO file_accessed(iocb->f_filp) */
+ return ret;
+}
+
+static bool file_extending_write(struct kiocb *iocb, struct iov_iter *from)
+{
+ struct inode *inode = file_inode(iocb->ki_filp);
+
+ return (iov_iter_rw(from) == WRITE &&
+ ((iocb->ki_pos) >= i_size_read(inode) ||
+ (iocb->ki_pos + iov_iter_count(from) > i_size_read(inode))));
+}
+
+static ssize_t fuse_dax_direct_write(struct kiocb *iocb, struct iov_iter *from)
+{
+ struct inode *inode = file_inode(iocb->ki_filp);
+ struct fuse_io_priv io = FUSE_IO_PRIV_SYNC(iocb);
+ ssize_t ret;
+
+ ret = fuse_direct_io(&io, from, &iocb->ki_pos, FUSE_DIO_WRITE);
+ if (ret < 0)
+ return ret;
+
+ fuse_invalidate_attr(inode);
+ fuse_write_update_size(inode, iocb->ki_pos);
+ return ret;
+}
+
+ssize_t fuse_dax_write_iter(struct kiocb *iocb, struct iov_iter *from)
+{
+ struct inode *inode = file_inode(iocb->ki_filp);
+ ssize_t ret;
+
+ if (iocb->ki_flags & IOCB_NOWAIT) {
+ if (!inode_trylock(inode))
+ return -EAGAIN;
+ } else {
+ inode_lock(inode);
+ }
+
+ ret = generic_write_checks(iocb, from);
+ if (ret <= 0)
+ goto out;
+
+ ret = file_remove_privs(iocb->ki_filp);
+ if (ret)
+ goto out;
+ /* TODO file_update_time() but we don't want metadata I/O */
+
+ /* Do not use dax for file extending writes as write and on
+ * disk i_size increase are not atomic otherwise.
+ */
+ if (file_extending_write(iocb, from))
+ ret = fuse_dax_direct_write(iocb, from);
+ else
+ ret = dax_iomap_rw(iocb, from, &fuse_iomap_ops);
+
+out:
+ inode_unlock(inode);
+
+ if (ret > 0)
+ ret = generic_write_sync(iocb, ret);
+ return ret;
+}
+
+static int fuse_dax_writepages(struct address_space *mapping,
+ struct writeback_control *wbc)
+{
+
+ struct inode *inode = mapping->host;
+ struct fuse_conn *fc = get_fuse_conn(inode);
+
+ return dax_writeback_mapping_range(mapping, fc->dax->dev, wbc);
+}
+
+static vm_fault_t __fuse_dax_fault(struct vm_fault *vmf,
+ enum page_entry_size pe_size, bool write)
+{
+ vm_fault_t ret;
+ struct inode *inode = file_inode(vmf->vma->vm_file);
+ struct super_block *sb = inode->i_sb;
+ pfn_t pfn;
+ int error = 0;
+ struct fuse_conn *fc = get_fuse_conn(inode);
+ struct fuse_conn_dax *fcd = fc->dax;
+ bool retry = false;
+
+ if (write)
+ sb_start_pagefault(sb);
+retry:
+ if (retry && !(fcd->nr_free_ranges > 0))
+ wait_event(fcd->range_waitq, (fcd->nr_free_ranges > 0));
+
+ /*
+ * We need to serialize against not only truncate but also against
+ * fuse dax memory range reclaim. While a range is being reclaimed,
+ * we do not want any read/write/mmap to make progress and try
+ * to populate page cache or access memory we are trying to free.
+ */
+ down_read(&get_fuse_inode(inode)->i_mmap_sem);
+ ret = dax_iomap_fault(vmf, pe_size, &pfn, &error, &fuse_iomap_ops);
+ if ((ret & VM_FAULT_ERROR) && error == -EAGAIN) {
+ error = 0;
+ retry = true;
+ up_read(&get_fuse_inode(inode)->i_mmap_sem);
+ goto retry;
+ }
+
+ if (ret & VM_FAULT_NEEDDSYNC)
+ ret = dax_finish_sync_fault(vmf, pe_size, pfn);
+ up_read(&get_fuse_inode(inode)->i_mmap_sem);
+
+ if (write)
+ sb_end_pagefault(sb);
+
+ return ret;
+}
+
+static vm_fault_t fuse_dax_fault(struct vm_fault *vmf)
+{
+ return __fuse_dax_fault(vmf, PE_SIZE_PTE,
+ vmf->flags & FAULT_FLAG_WRITE);
+}
+
+static vm_fault_t fuse_dax_huge_fault(struct vm_fault *vmf,
+ enum page_entry_size pe_size)
+{
+ return __fuse_dax_fault(vmf, pe_size, vmf->flags & FAULT_FLAG_WRITE);
+}
+
+static vm_fault_t fuse_dax_page_mkwrite(struct vm_fault *vmf)
+{
+ return __fuse_dax_fault(vmf, PE_SIZE_PTE, true);
+}
+
+static vm_fault_t fuse_dax_pfn_mkwrite(struct vm_fault *vmf)
+{
+ return __fuse_dax_fault(vmf, PE_SIZE_PTE, true);
+}
+
+static const struct vm_operations_struct fuse_dax_vm_ops = {
+ .fault = fuse_dax_fault,
+ .huge_fault = fuse_dax_huge_fault,
+ .page_mkwrite = fuse_dax_page_mkwrite,
+ .pfn_mkwrite = fuse_dax_pfn_mkwrite,
+};
+
+int fuse_dax_mmap(struct file *file, struct vm_area_struct *vma)
+{
+ file_accessed(file);
+ vma->vm_ops = &fuse_dax_vm_ops;
+ vma->vm_flags |= VM_MIXEDMAP | VM_HUGEPAGE;
+ return 0;
+}
+
+static int dmap_writeback_invalidate(struct inode *inode,
+ struct fuse_dax_mapping *dmap)
+{
+ int ret;
+ loff_t start_pos = dmap->itn.start << FUSE_DAX_SHIFT;
+ loff_t end_pos = (start_pos + FUSE_DAX_SZ - 1);
+
+ ret = filemap_fdatawrite_range(inode->i_mapping, start_pos, end_pos);
+ if (ret) {
+ pr_debug("fuse: filemap_fdatawrite_range() failed. err=%d start_pos=0x%llx, end_pos=0x%llx\n",
+ ret, start_pos, end_pos);
+ return ret;
+ }
+
+ ret = invalidate_inode_pages2_range(inode->i_mapping,
+ start_pos >> PAGE_SHIFT,
+ end_pos >> PAGE_SHIFT);
+ if (ret)
+ pr_debug("fuse: invalidate_inode_pages2_range() failed err=%d\n",
+ ret);
+
+ return ret;
+}
+
+static int reclaim_one_dmap_locked(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 */
+ interval_tree_remove(&dmap->itn, &fi->dax->tree);
+ fi->dax->nr--;
+
+ /* It is possible that umount/shutdown has killed the fuse connection
+ * and worker thread is trying to reclaim memory in parallel. Don't
+ * warn in that case.
+ */
+ ret = dmap_removemapping_one(inode, dmap);
+ if (ret && ret != -ENOTCONN) {
+ pr_warn("Failed to remove mapping. offset=0x%llx len=0x%llx ret=%d\n",
+ dmap->window_offset, dmap->length, ret);
+ }
+ return 0;
+}
+
+/* Find first mapped dmap for an inode and return file offset. Caller needs
+ * to hold fi->dax->sem lock either shared or exclusive.
+ */
+static struct fuse_dax_mapping *inode_lookup_first_dmap(struct inode *inode)
+{
+ struct fuse_inode *fi = get_fuse_inode(inode);
+ struct fuse_dax_mapping *dmap;
+ struct interval_tree_node *node;
+
+ for (node = interval_tree_iter_first(&fi->dax->tree, 0, -1); node;
+ node = interval_tree_iter_next(node, 0, -1)) {
+ dmap = node_to_dmap(node);
+ /* still in use. */
+ if (refcount_read(&dmap->refcnt) > 1)
+ continue;
+
+ return dmap;
+ }
+
+ return NULL;
+}
+
+/*
+ * Find first mapping in the tree and free it and return it. Do not add
+ * it back to free pool.
+ */
+static struct fuse_dax_mapping *
+inode_inline_reclaim_one_dmap(struct fuse_conn_dax *fcd, struct inode *inode,
+ bool *retry)
+{
+ struct fuse_inode *fi = get_fuse_inode(inode);
+ struct fuse_dax_mapping *dmap;
+ u64 dmap_start, dmap_end;
+ unsigned long start_idx;
+ int ret;
+ struct interval_tree_node *node;
+
+ down_write(&fi->i_mmap_sem);
+
+ /* Lookup a dmap and corresponding file offset to reclaim. */
+ down_read(&fi->dax->sem);
+ dmap = inode_lookup_first_dmap(inode);
+ if (dmap) {
+ start_idx = dmap->itn.start;
+ dmap_start = start_idx << FUSE_DAX_SHIFT;
+ dmap_end = dmap_start + FUSE_DAX_SZ - 1;
+ }
+ up_read(&fi->dax->sem);
+
+ if (!dmap)
+ goto out_mmap_sem;
+ /*
+ * Make sure there are no references to inode pages using
+ * get_user_pages()
+ */
+ ret = fuse_dax_break_layouts(inode, dmap_start, dmap_end);
+ if (ret) {
+ pr_debug("fuse: fuse_dax_break_layouts() failed. err=%d\n",
+ ret);
+ dmap = ERR_PTR(ret);
+ goto out_mmap_sem;
+ }
+
+ down_write(&fi->dax->sem);
+ node = interval_tree_iter_first(&fi->dax->tree, start_idx, start_idx);
+ /* Range already got reclaimed by somebody else */
+ if (!node) {
+ if (retry)
+ *retry = true;
+ goto out_write_dmap_sem;
+ }
+
+ dmap = node_to_dmap(node);
+ /* still in use. */
+ if (refcount_read(&dmap->refcnt) > 1) {
+ dmap = NULL;
+ if (retry)
+ *retry = true;
+ goto out_write_dmap_sem;
+ }
+
+ ret = reclaim_one_dmap_locked(inode, dmap);
+ if (ret < 0) {
+ dmap = ERR_PTR(ret);
+ goto out_write_dmap_sem;
+ }
+
+ /* Clean up dmap. Do not add back to free list */
+ dmap_remove_busy_list(fcd, dmap);
+ dmap->inode = NULL;
+ dmap->itn.start = dmap->itn.last = 0;
+
+ pr_debug("fuse: %s: inline reclaimed memory range. inode=%p, window_offset=0x%llx, length=0x%llx\n",
+ __func__, inode, dmap->window_offset, dmap->length);
+
+out_write_dmap_sem:
+ up_write(&fi->dax->sem);
+out_mmap_sem:
+ up_write(&fi->i_mmap_sem);
+ return dmap;
+}
+
+static struct fuse_dax_mapping *
+alloc_dax_mapping_reclaim(struct fuse_conn_dax *fcd, struct inode *inode)
+{
+ struct fuse_dax_mapping *dmap;
+ struct fuse_inode *fi = get_fuse_inode(inode);
+
+ while (1) {
+ bool retry = false;
+
+ dmap = alloc_dax_mapping(fcd);
+ if (dmap)
+ return dmap;
+
+ dmap = inode_inline_reclaim_one_dmap(fcd, inode, &retry);
+ /*
+ * Either we got a mapping or it is an error, return in both
+ * the cases.
+ */
+ if (dmap)
+ return dmap;
+
+ /* If we could not reclaim a mapping because it
+ * had a reference or some other temporary failure,
+ * Try again. We want to give up inline reclaim only
+ * if there is no range assigned to this node. Otherwise
+ * if a deadlock is possible if we sleep with fi->i_mmap_sem
+ * held and worker to free memory can't make progress due
+ * to unavailability of fi->i_mmap_sem lock. So sleep
+ * only if fi->dax->nr=0
+ */
+ if (retry)
+ continue;
+ /*
+ * There are no mappings which can be reclaimed. Wait for one.
+ * We are not holding fi->dax->sem. So it is possible
+ * that range gets added now. But as we are not holding
+ * fi->i_mmap_sem, worker should still be able to free up
+ * a range and wake us up.
+ */
+ if (!fi->dax->nr && !(fcd->nr_free_ranges > 0)) {
+ if (wait_event_killable_exclusive(fcd->range_waitq,
+ (fcd->nr_free_ranges > 0))) {
+ return ERR_PTR(-EINTR);
+ }
+ }
+ }
+}
+
+static int lookup_and_reclaim_dmap_locked(struct fuse_conn_dax *fcd,
+ struct inode *inode,
+ unsigned long start_idx)
+{
+ int ret;
+ struct fuse_inode *fi = get_fuse_inode(inode);
+ struct fuse_dax_mapping *dmap;
+ struct interval_tree_node *node;
+
+ /* Find fuse dax mapping at file offset inode. */
+ node = interval_tree_iter_first(&fi->dax->tree, start_idx, start_idx);
+
+ /* Range already got cleaned up by somebody else */
+ if (!node)
+ return 0;
+ dmap = node_to_dmap(node);
+
+ /* still in use. */
+ if (refcount_read(&dmap->refcnt) > 1)
+ return 0;
+
+ ret = reclaim_one_dmap_locked(inode, dmap);
+ if (ret < 0)
+ return ret;
+
+ /* Cleanup dmap entry and add back to free list */
+ spin_lock(&fcd->lock);
+ dmap_reinit_add_to_free_pool(fcd, dmap);
+ spin_unlock(&fcd->lock);
+ return ret;
+}
+
+/*
+ * Free a range of memory.
+ * Locking:
+ * 1. Take fi->i_mmap_sem to block dax faults.
+ * 2. Take fi->dax->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_dax *fcd,
+ struct inode *inode,
+ unsigned long start_idx,
+ unsigned long end_idx)
+{
+ int ret;
+ struct fuse_inode *fi = get_fuse_inode(inode);
+ loff_t dmap_start = start_idx << FUSE_DAX_SHIFT;
+ loff_t dmap_end = (dmap_start + FUSE_DAX_SZ) - 1;
+
+ down_write(&fi->i_mmap_sem);
+ ret = fuse_dax_break_layouts(inode, dmap_start, dmap_end);
+ if (ret) {
+ pr_debug("virtio_fs: fuse_dax_break_layouts() failed. err=%d\n",
+ ret);
+ goto out_mmap_sem;
+ }
+
+ down_write(&fi->dax->sem);
+ ret = lookup_and_reclaim_dmap_locked(fcd, inode, start_idx);
+ up_write(&fi->dax->sem);
+out_mmap_sem:
+ up_write(&fi->i_mmap_sem);
+ return ret;
+}
+
+static int try_to_free_dmap_chunks(struct fuse_conn_dax *fcd,
+ unsigned long nr_to_free)
+{
+ struct fuse_dax_mapping *dmap, *pos, *temp;
+ int ret, nr_freed = 0;
+ unsigned long start_idx = 0, end_idx = 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(&fcd->lock);
+
+ if (!fcd->nr_busy_ranges) {
+ spin_unlock(&fcd->lock);
+ return 0;
+ }
+
+ list_for_each_entry_safe(pos, temp, &fcd->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, &fcd->busy_ranges);
+ start_idx = end_idx = dmap->itn.start;
+ break;
+ }
+ spin_unlock(&fcd->lock);
+ if (!dmap)
+ return 0;
+
+ ret = lookup_and_reclaim_dmap(fcd, inode, start_idx, end_idx);
+ iput(inode);
+ if (ret)
+ return ret;
+ nr_freed++;
+ }
+ return 0;
+}
+
+static void fuse_dax_free_mem_worker(struct work_struct *work)
+{
+ int ret;
+ struct fuse_conn_dax *fcd = container_of(work, struct fuse_conn_dax,
+ free_work.work);
+ ret = try_to_free_dmap_chunks(fcd, 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(fcd, 1);
+}
+
static void fuse_free_dax_mem_ranges(struct list_head *mem_list)
{
struct fuse_dax_mapping *range, *temp;
/* Free All allocated elements */
list_for_each_entry_safe(range, temp, mem_list, list) {
list_del(&range->list);
+ if (!list_empty(&range->busy_list))
+ list_del(&range->busy_list);
kfree(range);
}
}
size_t dax_size = -1;
unsigned long i;
+ init_waitqueue_head(&fcd->range_waitq);
INIT_LIST_HEAD(&fcd->free_ranges);
+ INIT_LIST_HEAD(&fcd->busy_ranges);
+ INIT_DELAYED_WORK(&fcd->free_work, fuse_dax_free_mem_worker);
+
id = dax_read_lock();
nr_pages = dax_direct_access(fcd->dev, 0, PHYS_PFN(dax_size), &kaddr,
&pfn);
*/
range->window_offset = i * FUSE_DAX_SZ;
range->length = FUSE_DAX_SZ;
+ INIT_LIST_HEAD(&range->busy_list);
+ refcount_set(&range->refcnt, 1);
list_add_tail(&range->list, &fcd->free_ranges);
}
fcd->nr_free_ranges = nr_ranges;
+ fcd->nr_ranges = nr_ranges;
return 0;
out_err:
/* Free All allocated elements */
if (!fcd)
return -ENOMEM;
+ spin_lock_init(&fcd->lock);
fcd->dev = dax_dev;
err = fuse_dax_mem_range_init(fcd);
if (err) {
fc->dax = fcd;
return 0;
}
+
+bool fuse_dax_inode_alloc(struct super_block *sb, struct fuse_inode *fi)
+{
+ struct fuse_conn *fc = get_fuse_conn_super(sb);
+
+ fi->dax = NULL;
+ if (fc->dax) {
+ fi->dax = kzalloc(sizeof(*fi->dax), GFP_KERNEL_ACCOUNT);
+ if (!fi->dax)
+ return false;
+
+ init_rwsem(&fi->dax->sem);
+ fi->dax->tree = RB_ROOT_CACHED;
+ }
+
+ return true;
+}
+
+static const struct address_space_operations fuse_dax_file_aops = {
+ .writepages = fuse_dax_writepages,
+ .direct_IO = noop_direct_IO,
+ .set_page_dirty = noop_set_page_dirty,
+ .invalidatepage = noop_invalidatepage,
+};
+
+void fuse_dax_inode_init(struct inode *inode)
+{
+ struct fuse_conn *fc = get_fuse_conn(inode);
+
+ if (!fc->dax)
+ return;
+
+ inode->i_flags |= S_DAX;
+ inode->i_data.a_ops = &fuse_dax_file_aops;
+}
+
+bool fuse_dax_check_alignment(struct fuse_conn *fc, unsigned int map_alignment)
+{
+ if (fc->dax && (map_alignment > FUSE_DAX_SHIFT)) {
+ pr_warn("FUSE: map_alignment %u incompatible with dax mem range size %u\n",
+ map_alignment, FUSE_DAX_SZ);
+ return false;
+ }
+ return true;
+}
+
+void fuse_dax_cancel_work(struct fuse_conn *fc)
+{
+ struct fuse_conn_dax *fcd = fc->dax;
+
+ if (fcd)
+ cancel_delayed_work_sync(&fcd->free_work);
+
+}
+EXPORT_SYMBOL_GPL(fuse_dax_cancel_work);
projects / mirror_ubuntu-jammy-kernel.git / blobdiff