Upon completion of an OPEN, if we're in famfs-mode we do a GET_FMAP to retrieve and cache up the file-to-dax map in the kernel. If this succeeds, read/write/mmap are resolved direct-to-dax with no upcalls.
GET_FMAP has a variable-size response payload, and the allocated size is sent in the in_args[0].size field. If the fmap would overflow the message, the fuse server sends a reply of size 'sizeof(uint32_t)' which specifies the size of the fmap message. Then the kernel can realloc a large enough buffer and try again. Signed-off-by: John Groves <[email protected]> --- fs/fuse/file.c | 84 +++++++++++++++++++++++++++++++++++++++ fs/fuse/fuse_i.h | 36 ++++++++++++++++- fs/fuse/inode.c | 19 +++++++-- fs/fuse/iomode.c | 2 +- include/uapi/linux/fuse.h | 18 +++++++++ 5 files changed, 154 insertions(+), 5 deletions(-) diff --git a/fs/fuse/file.c b/fs/fuse/file.c index 93b82660f0c8..8616fb0a6d61 100644 --- a/fs/fuse/file.c +++ b/fs/fuse/file.c @@ -230,6 +230,77 @@ static void fuse_truncate_update_attr(struct inode *inode, struct file *file) fuse_invalidate_attr_mask(inode, FUSE_STATX_MODSIZE); } +#if IS_ENABLED(CONFIG_FUSE_FAMFS_DAX) + +#define FMAP_BUFSIZE 4096 + +static int +fuse_get_fmap(struct fuse_mount *fm, struct inode *inode, u64 nodeid) +{ + struct fuse_get_fmap_in inarg = { 0 }; + size_t fmap_bufsize = FMAP_BUFSIZE; + ssize_t fmap_size; + int retries = 1; + void *fmap_buf; + int rc; + + FUSE_ARGS(args); + + fmap_buf = kcalloc(1, FMAP_BUFSIZE, GFP_KERNEL); + if (!fmap_buf) + return -EIO; + + retry_once: + inarg.size = fmap_bufsize; + + args.opcode = FUSE_GET_FMAP; + args.nodeid = nodeid; + + args.in_numargs = 1; + args.in_args[0].size = sizeof(inarg); + args.in_args[0].value = &inarg; + + /* Variable-sized output buffer + * this causes fuse_simple_request() to return the size of the + * output payload + */ + args.out_argvar = true; + args.out_numargs = 1; + args.out_args[0].size = fmap_bufsize; + args.out_args[0].value = fmap_buf; + + /* Send GET_FMAP command */ + rc = fuse_simple_request(fm, &args); + if (rc < 0) { + pr_err("%s: err=%d from fuse_simple_request()\n", + __func__, rc); + return rc; + } + fmap_size = rc; + + if (retries && fmap_size == sizeof(uint32_t)) { + /* fmap size exceeded fmap_bufsize; + * actual fmap size returned in fmap_buf; + * realloc and retry once + */ + fmap_bufsize = *((uint32_t *)fmap_buf); + + --retries; + kfree(fmap_buf); + fmap_buf = kcalloc(1, fmap_bufsize, GFP_KERNEL); + if (!fmap_buf) + return -EIO; + + goto retry_once; + } + + /* Will call famfs_file_init_dax() when that gets added */ + + kfree(fmap_buf); + return 0; +} +#endif + static int fuse_open(struct inode *inode, struct file *file) { struct fuse_mount *fm = get_fuse_mount(inode); @@ -263,6 +334,19 @@ static int fuse_open(struct inode *inode, struct file *file) err = fuse_do_open(fm, get_node_id(inode), file, false); if (!err) { +#if IS_ENABLED(CONFIG_FUSE_FAMFS_DAX) + if (fm->fc->famfs_iomap) { + if (S_ISREG(inode->i_mode)) { + int rc; + /* Get the famfs fmap */ + rc = fuse_get_fmap(fm, inode, + get_node_id(inode)); + if (rc) + pr_err("%s: fuse_get_fmap err=%d\n", + __func__, rc); + } + } +#endif ff = file->private_data; err = fuse_finish_open(inode, file); if (err) diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h index f4ee61046578..e01d6e5c6e93 100644 --- a/fs/fuse/fuse_i.h +++ b/fs/fuse/fuse_i.h @@ -193,6 +193,10 @@ struct fuse_inode { /** Reference to backing file in passthrough mode */ struct fuse_backing *fb; #endif + +#if IS_ENABLED(CONFIG_FUSE_FAMFS_DAX) + void *famfs_meta; +#endif }; /** FUSE inode state bits */ @@ -945,6 +949,8 @@ struct fuse_conn { #endif #if IS_ENABLED(CONFIG_FUSE_FAMFS_DAX) + struct rw_semaphore famfs_devlist_sem; + struct famfs_dax_devlist *dax_devlist; char *shadow; #endif }; @@ -1435,11 +1441,14 @@ void fuse_free_conn(struct fuse_conn *fc); /* dax.c */ +static inline int fuse_file_famfs(struct fuse_inode *fi); /* forward */ + /* This macro is used by virtio_fs, but now it also needs to filter for * "not famfs" */ #define FUSE_IS_VIRTIO_DAX(fuse_inode) (IS_ENABLED(CONFIG_FUSE_DAX) \ - && IS_DAX(&fuse_inode->inode)) + && IS_DAX(&fuse_inode->inode) \ + && !fuse_file_famfs(fuse_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); @@ -1550,4 +1559,29 @@ extern void fuse_sysctl_unregister(void); #define fuse_sysctl_unregister() do { } while (0) #endif /* CONFIG_SYSCTL */ +/* famfs.c */ +static inline struct fuse_backing *famfs_meta_set(struct fuse_inode *fi, + void *meta) +{ +#if IS_ENABLED(CONFIG_FUSE_FAMFS_DAX) + return xchg(&fi->famfs_meta, meta); +#else + return NULL; +#endif +} + +static inline void famfs_meta_free(struct fuse_inode *fi) +{ + /* Stub wil be connected in a subsequent commit */ +} + +static inline int fuse_file_famfs(struct fuse_inode *fi) +{ +#if IS_ENABLED(CONFIG_FUSE_FAMFS_DAX) + return (READ_ONCE(fi->famfs_meta) != NULL); +#else + return 0; +#endif +} + #endif /* _FS_FUSE_I_H */ diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c index a7e1cf8257b0..b071d16f7d04 100644 --- a/fs/fuse/inode.c +++ b/fs/fuse/inode.c @@ -117,6 +117,9 @@ static struct inode *fuse_alloc_inode(struct super_block *sb) if (IS_ENABLED(CONFIG_FUSE_PASSTHROUGH)) fuse_inode_backing_set(fi, NULL); + if (IS_ENABLED(CONFIG_FUSE_FAMFS_DAX)) + famfs_meta_set(fi, NULL); + return &fi->inode; out_free_forget: @@ -138,6 +141,13 @@ static void fuse_free_inode(struct inode *inode) if (IS_ENABLED(CONFIG_FUSE_PASSTHROUGH)) fuse_backing_put(fuse_inode_backing(fi)); +#if IS_ENABLED(CONFIG_FUSE_FAMFS_DAX) + if (S_ISREG(inode->i_mode) && fi->famfs_meta) { + famfs_meta_free(fi); + famfs_meta_set(fi, NULL); + } +#endif + kmem_cache_free(fuse_inode_cachep, fi); } @@ -1002,6 +1012,9 @@ void fuse_conn_init(struct fuse_conn *fc, struct fuse_mount *fm, if (IS_ENABLED(CONFIG_FUSE_PASSTHROUGH)) fuse_backing_files_init(fc); + if (IS_ENABLED(CONFIG_FUSE_FAMFS_DAX)) + pr_notice("%s: Kernel is FUSE_FAMFS_DAX capable\n", __func__); + INIT_LIST_HEAD(&fc->mounts); list_add(&fm->fc_entry, &fc->mounts); fm->fc = fc; @@ -1036,9 +1049,8 @@ void fuse_conn_put(struct fuse_conn *fc) } if (IS_ENABLED(CONFIG_FUSE_PASSTHROUGH)) fuse_backing_files_free(fc); -#if IS_ENABLED(CONFIG_FUSE_FAMFS_DAX) - kfree(fc->shadow); -#endif + if (IS_ENABLED(CONFIG_FUSE_FAMFS_DAX)) + kfree(fc->shadow); call_rcu(&fc->rcu, delayed_release); } } @@ -1425,6 +1437,7 @@ static void process_init_reply(struct fuse_mount *fm, struct fuse_args *args, * those capabilities, they are held here). */ fc->famfs_iomap = 1; + init_rwsem(&fc->famfs_devlist_sem); } } else { ra_pages = fc->max_read / PAGE_SIZE; diff --git a/fs/fuse/iomode.c b/fs/fuse/iomode.c index aec4aecb5d79..443b337b0c05 100644 --- a/fs/fuse/iomode.c +++ b/fs/fuse/iomode.c @@ -204,7 +204,7 @@ int fuse_file_io_open(struct file *file, struct inode *inode) * io modes are not relevant with DAX and with server that does not * implement open. */ - if (FUSE_IS_VIRTIO_DAX(fi) || !ff->args) + if (FUSE_IS_VIRTIO_DAX(fi) || fuse_file_famfs(fi) || !ff->args) return 0; /* diff --git a/include/uapi/linux/fuse.h b/include/uapi/linux/fuse.h index 6c384640c79b..dff5aa62543e 100644 --- a/include/uapi/linux/fuse.h +++ b/include/uapi/linux/fuse.h @@ -654,6 +654,10 @@ enum fuse_opcode { FUSE_TMPFILE = 51, FUSE_STATX = 52, + /* Famfs / devdax opcodes */ + FUSE_GET_FMAP = 53, + FUSE_GET_DAXDEV = 54, + /* CUSE specific operations */ CUSE_INIT = 4096, @@ -888,6 +892,16 @@ struct fuse_access_in { uint32_t padding; }; +struct fuse_get_fmap_in { + uint32_t size; + uint32_t padding; +}; + +struct fuse_get_fmap_out { + uint32_t size; + uint32_t padding; +}; + struct fuse_init_in { uint32_t major; uint32_t minor; @@ -1284,4 +1298,8 @@ struct fuse_uring_cmd_req { uint8_t padding[6]; }; +/* Famfs fmap message components */ + +#define FAMFS_FMAP_MAX 32768 /* Largest supported fmap message */ + #endif /* _LINUX_FUSE_H */ -- 2.49.0
