diff --git a/fs/fuse/Kconfig b/fs/fuse/Kconfig index fddd40630077..40ce9a1c12e5 100644 --- a/fs/fuse/Kconfig +++ b/fs/fuse/Kconfig @@ -42,6 +42,7 @@ config VIRTIO_FS config FUSE_DAX bool "Virtio Filesystem Direct Host Memory Access support" default y + select INTERVAL_TREE depends on VIRTIO_FS depends on FS_DAX depends on DAX_DRIVER diff --git a/fs/fuse/dax.c b/fs/fuse/dax.c index fec8a2bd75b3..a8d311b2db8e 100644 --- a/fs/fuse/dax.c +++ b/fs/fuse/dax.c @@ -7,7 +7,10 @@ #include "fuse_i.h" #include +#include #include +#include +#include /* * Default memory range size. A power of 2 so it agrees with common FUSE_INIT @@ -22,22 +25,556 @@ struct fuse_dax_mapping { /* 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; + /** 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; +}; + +/* 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; + /* DAX Window Free Ranges */ long nr_free_ranges; struct list_head free_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(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); + return dmap; +} + +/* 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++; +} + +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_conn *fc = get_fuse_conn(inode); + struct fuse_conn_dax *fcd = 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(fc, &args); + if (err < 0) + return err; + dmap->writable = writable; + if (!upgrade) { + dmap->itn.start = dmap->itn.last = start_idx; + /* Protected by fi->dax->sem */ + interval_tree_insert(&dmap->itn, &fi->dax->tree); + fi->dax->nr++; + } + 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_conn *fc = get_fuse_conn(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(fc, &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->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); + 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); +} + +/* + * 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; + } 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; + + alloc_dmap = alloc_dax_mapping(fcd); + if (!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 reclaimed or truncated and it should still + * be there in tree despite the fact we dropped and re-acquired the + * lock. + */ + ret = -EIO; + if (WARN_ON(!node)) + goto out_err; + + dmap = node_to_dmap(node); + + /* 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. + */ + 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) +{ + /* 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, +}; + +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 void fuse_free_dax_mem_ranges(struct list_head *mem_list) { struct fuse_dax_mapping *range, *temp; @@ -116,6 +653,7 @@ int fuse_dax_conn_alloc(struct fuse_conn *fc, struct dax_device *dax_dev) if (!fcd) return -ENOMEM; + spin_lock_init(&fcd->lock); fcd->dev = dax_dev; err = fuse_dax_mem_range_init(fcd); if (err) { @@ -127,6 +665,33 @@ int fuse_dax_conn_alloc(struct fuse_conn *fc, struct dax_device *dax_dev) 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; +} + +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; +} + bool fuse_dax_check_alignment(struct fuse_conn *fc, unsigned int map_alignment) { if (fc->dax && (map_alignment > FUSE_DAX_SHIFT)) { diff --git a/fs/fuse/file.c b/fs/fuse/file.c index 6611ef3269a8..6c586bc97b64 100644 --- a/fs/fuse/file.c +++ b/fs/fuse/file.c @@ -1539,10 +1539,14 @@ static ssize_t fuse_file_read_iter(struct kiocb *iocb, struct iov_iter *to) { struct file *file = iocb->ki_filp; struct fuse_file *ff = file->private_data; + struct inode *inode = file_inode(file); - if (is_bad_inode(file_inode(file))) + if (is_bad_inode(inode)) return -EIO; + if (FUSE_IS_DAX(inode)) + return fuse_dax_read_iter(iocb, to); + if (!(ff->open_flags & FOPEN_DIRECT_IO)) return fuse_cache_read_iter(iocb, to); else @@ -1553,10 +1557,14 @@ static ssize_t fuse_file_write_iter(struct kiocb *iocb, struct iov_iter *from) { struct file *file = iocb->ki_filp; struct fuse_file *ff = file->private_data; + struct inode *inode = file_inode(file); - if (is_bad_inode(file_inode(file))) + if (is_bad_inode(inode)) return -EIO; + if (FUSE_IS_DAX(inode)) + return fuse_dax_write_iter(iocb, from); + if (!(ff->open_flags & FOPEN_DIRECT_IO)) return fuse_cache_write_iter(iocb, from); else @@ -3440,4 +3448,7 @@ void fuse_init_file_inode(struct inode *inode) fi->writectr = 0; init_waitqueue_head(&fi->page_waitq); fi->writepages = RB_ROOT; + + if (IS_ENABLED(CONFIG_FUSE_DAX)) + fuse_dax_inode_init(inode); } diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h index 2f3f04aa64c7..2d2bdd596194 100644 --- a/fs/fuse/fuse_i.h +++ b/fs/fuse/fuse_i.h @@ -148,6 +148,13 @@ struct fuse_inode { /** Lock to protect write related fields */ spinlock_t lock; + +#ifdef CONFIG_FUSE_DAX + /* + * Dax specific inode data + */ + struct fuse_inode_dax *dax; +#endif }; /** FUSE inode state bits */ @@ -1104,8 +1111,16 @@ void fuse_free_conn(struct fuse_conn *fc); /* dax.c */ +#define FUSE_IS_DAX(inode) (IS_ENABLED(CONFIG_FUSE_DAX) && IS_DAX(inode)) + +ssize_t fuse_dax_read_iter(struct kiocb *iocb, struct iov_iter *to); +ssize_t fuse_dax_write_iter(struct kiocb *iocb, struct iov_iter *from); +int fuse_dax_mmap(struct file *file, struct vm_area_struct *vma); int fuse_dax_conn_alloc(struct fuse_conn *fc, struct dax_device *dax_dev); void fuse_dax_conn_free(struct fuse_conn *fc); +bool fuse_dax_inode_alloc(struct super_block *sb, struct fuse_inode *fi); +void fuse_dax_inode_init(struct inode *inode); +void fuse_dax_inode_cleanup(struct inode *inode); bool fuse_dax_check_alignment(struct fuse_conn *fc, unsigned int map_alignment); #endif /* _FS_FUSE_I_H */ diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c index 67e99cee5a4f..cab4239bd78a 100644 --- a/fs/fuse/inode.c +++ b/fs/fuse/inode.c @@ -87,12 +87,19 @@ static struct inode *fuse_alloc_inode(struct super_block *sb) mutex_init(&fi->mutex); spin_lock_init(&fi->lock); fi->forget = fuse_alloc_forget(); - if (!fi->forget) { - kmem_cache_free(fuse_inode_cachep, fi); - return NULL; - } + if (!fi->forget) + goto out_free; + + if (IS_ENABLED(CONFIG_FUSE_DAX) && !fuse_dax_inode_alloc(sb, fi)) + goto out_free_forget; return &fi->inode; + +out_free_forget: + kfree(fi->forget); +out_free: + kmem_cache_free(fuse_inode_cachep, fi); + return NULL; } static void fuse_free_inode(struct inode *inode) @@ -101,6 +108,9 @@ static void fuse_free_inode(struct inode *inode) mutex_destroy(&fi->mutex); kfree(fi->forget); +#ifdef CONFIG_FUSE_DAX + kfree(fi->dax); +#endif kmem_cache_free(fuse_inode_cachep, fi); } @@ -112,6 +122,9 @@ static void fuse_evict_inode(struct inode *inode) clear_inode(inode); if (inode->i_sb->s_flags & SB_ACTIVE) { struct fuse_conn *fc = get_fuse_conn(inode); + + if (FUSE_IS_DAX(inode)) + fuse_dax_inode_cleanup(inode); fuse_queue_forget(fc, fi->forget, fi->nodeid, fi->nlookup); fi->forget = NULL; } diff --git a/include/uapi/linux/fuse.h b/include/uapi/linux/fuse.h index 60a7bfc787ce..8899e4862309 100644 --- a/include/uapi/linux/fuse.h +++ b/include/uapi/linux/fuse.h @@ -895,6 +895,7 @@ struct fuse_copy_file_range_in { }; #define FUSE_SETUPMAPPING_FLAG_WRITE (1ull << 0) +#define FUSE_SETUPMAPPING_FLAG_READ (1ull << 1) struct fuse_setupmapping_in { /* An already open handle */ uint64_t fh;