From: John Groves <[email protected]> Fill in read/write/mmap handling for famfs files using the dev_dax_iomap interface, the same path xfs uses in fs-dax mode.
- Read/write go through famfs_fuse_[read|write]_iter() via dax_iomap_rw() to fsdev_dax. - Mmap is handled by famfs_fuse_mmap(). - Faults are handled by famfs_filemap_fault() via dax_iomap_fault() to fsdev_dax. - File-offset-to-dax-offset resolution is handled by famfs_fuse_iomap_begin(), which uses the file's fmap to resolve a (file, offset) to an offset on a dax device via famfs_fileofs_to_daxofs(). Signed-off-by: John Groves <[email protected]> --- fs/fuse/famfs.c | 337 ++++++++++++++++++++++++++++++++++++++++++++++- fs/fuse/file.c | 18 ++- fs/fuse/fuse_i.h | 19 +++ 3 files changed, 371 insertions(+), 3 deletions(-) diff --git a/fs/fuse/famfs.c b/fs/fuse/famfs.c index a2a7dd631dc0..ac56317944d9 100644 --- a/fs/fuse/famfs.c +++ b/fs/fuse/famfs.c @@ -580,7 +580,342 @@ famfs_file_init_dax( return rc; } -#define FMAP_BUFSIZE PAGE_SIZE +/********************************************************************* + * iomap_operations + * + * This stuff uses the iomap (dax-related) helpers to resolve file offsets to + * offsets within a dax device. + */ + +static int famfs_file_bad(struct inode *inode); + +/** + * famfs_fileofs_to_daxofs() - Resolve (file, offset, len) to (daxdev, offset, len) + * + * This function is called by famfs_fuse_iomap_begin() to resolve an offset in a + * file to an offset in a dax device. This is upcalled from dax from calls to + * both * dax_iomap_fault() and dax_iomap_rw(). Dax finishes the job resolving + * a fault to a specific physical page (the fault case) or doing a memcpy + * variant (the rw case) + * + * Pages can be PTE (4k), PMD (2MiB) or (theoretically) PuD (1GiB) + * (these sizes are for X86; may vary on other cpu architectures + * + * @inode: The file where the fault occurred + * @iomap: To be filled in to indicate where to find the right memory, + * relative to a dax device. + * @file_offset: Within the file where the fault occurred (will be page boundary) + * @len: The length of the faulted mapping (will be a page multiple) + * (will be trimmed in *iomap if it's disjoint in the extent list) + * @flags: flags passed to famfs_fuse_iomap_begin(), and sent back via + * struct iomap + * + * Return values: 0 on success, with the result in the modified @iomap struct. + * -EIO if (file_offset, len) cannot be resolved to a dax extent, + * which includes access past EOF (the caller turns this into a + * short read/write or a SIGBUS). + */ +static int +famfs_fileofs_to_daxofs(struct inode *inode, struct iomap *iomap, + loff_t file_offset, off_t len, unsigned int flags) +{ + struct fuse_inode *fi = get_fuse_inode(inode); + struct famfs_file_meta *meta = fi->famfs_meta; + struct fuse_conn *fc = get_fuse_conn(inode); + loff_t local_offset = file_offset; + u64 i; + + if (!fc->dax_devlist) { + pr_err("%s: null dax_devlist\n", __func__); + goto err_out; + } + + if (famfs_file_bad(inode)) + goto err_out; + + iomap->offset = file_offset; + + if (meta->ext_shift) { + /* + * Uniform extent size (detected at parse time): the containing + * extent index is a shift of the file offset, so resolve in + * O(1) instead of walking the extent list. + */ + u64 ext_size = 1ULL << meta->ext_shift; + + i = file_offset >> meta->ext_shift; + local_offset = file_offset & (ext_size - 1); + } else { + /* Single extent or non-uniform list: walk it */ + for (i = 0; i < meta->fm_nextents; i++) { + if (local_offset < meta->se[i].ext_len) + break; + local_offset -= meta->se[i].ext_len; + } + } + + /* local_offset is now the offset within extent i (if i is in range) */ + if (i < meta->fm_nextents && local_offset < meta->se[i].ext_len) { + loff_t dax_ext_offset = meta->se[i].ext_offset; + loff_t dax_ext_len = meta->se[i].ext_len; + u64 daxdev_idx = meta->se[i].dev_index; + loff_t ext_len_remainder = dax_ext_len - local_offset; + struct famfs_daxdev *dd; + + if (daxdev_idx >= fc->dax_devlist->nslots) { + pr_err("%s: daxdev_idx %llu >= nslots %d\n", + __func__, daxdev_idx, fc->dax_devlist->nslots); + goto err_out; + } + + dd = &fc->dax_devlist->devlist[daxdev_idx]; + + iomap->addr = dax_ext_offset + local_offset; + iomap->offset = file_offset; + iomap->length = min_t(loff_t, len, ext_len_remainder); + iomap->dax_dev = dd->devp; + iomap->type = IOMAP_MAPPED; + iomap->flags = flags; + return 0; + } + + err_out: + /* + * We fell out the end of the extent list, i.e. the access is past EOF. + * This is a normal, unprivileged-reachable condition (e.g. a fault in + * the tail of a mapping that extends past EOF), so log at debug level. + * The specific error cases above (null dax_devlist, bad daxdev index) + * have already logged at error level before jumping here. + */ + pr_debug("%s: could not resolve file_offset %lld (past EOF?)\n", + __func__, (long long)file_offset); + + /* + * Return a zero-length mapping and -EIO. dax turns this into a short + * read/write or a SIGBUS rather than touching dax memory. + */ + iomap->addr = 0; /* there is no valid dax device offset */ + iomap->offset = file_offset; /* file offset */ + iomap->length = 0; /* this had better result in no access to dax mem */ + iomap->dax_dev = NULL; + iomap->type = IOMAP_MAPPED; + iomap->flags = flags; + + return -EIO; +} + +/** + * famfs_fuse_iomap_begin() - Handler for iomap_begin upcall from dax + * + * This function is pretty simple because files are + * * never partially allocated + * * never have holes (never sparse) + * * never "allocate on write" + * + * @inode: inode for the file being accessed + * @offset: offset within the file + * @length: Length being accessed at offset + * @flags: flags to be retured via struct iomap + * @iomap: iomap struct to be filled in, resolving (offset, length) to + * (daxdev, offset, len) + * @srcmap: source mapping if it is a COW operation (which it is not here) + */ +static int +famfs_fuse_iomap_begin(struct inode *inode, loff_t offset, loff_t length, + unsigned int flags, struct iomap *iomap, struct iomap *srcmap) +{ + return famfs_fileofs_to_daxofs(inode, iomap, offset, length, flags); +} + +/* Note: We never need a special set of write_iomap_ops because famfs never + * performs allocation on write. + */ +const struct iomap_ops famfs_iomap_ops = { + .iomap_begin = famfs_fuse_iomap_begin, +}; + +/********************************************************************* + * vm_operations + */ +static vm_fault_t +__famfs_fuse_filemap_fault(struct vm_fault *vmf, unsigned int order, + bool write_fault) +{ + struct inode *inode = file_inode(vmf->vma->vm_file); + vm_fault_t ret; + unsigned long pfn; + + if (!IS_DAX(file_inode(vmf->vma->vm_file))) { + pr_err("%s: file not marked IS_DAX!!\n", __func__); + return VM_FAULT_SIGBUS; + } + + if (write_fault) { + sb_start_pagefault(inode->i_sb); + file_update_time(vmf->vma->vm_file); + } + + ret = dax_iomap_fault(vmf, order, &pfn, NULL, &famfs_iomap_ops); + if (ret & VM_FAULT_NEEDDSYNC) + ret = dax_finish_sync_fault(vmf, order, pfn); + + if (write_fault) + sb_end_pagefault(inode->i_sb); + + return ret; +} + +static inline bool +famfs_is_write_fault(struct vm_fault *vmf) +{ + return (vmf->flags & FAULT_FLAG_WRITE) && + (vmf->vma->vm_flags & VM_SHARED); +} + +static vm_fault_t +famfs_filemap_fault(struct vm_fault *vmf) +{ + return __famfs_fuse_filemap_fault(vmf, 0, famfs_is_write_fault(vmf)); +} + +static vm_fault_t +famfs_filemap_huge_fault(struct vm_fault *vmf, unsigned int order) +{ + return __famfs_fuse_filemap_fault(vmf, order, + famfs_is_write_fault(vmf)); +} + +static vm_fault_t +famfs_filemap_mkwrite(struct vm_fault *vmf) +{ + return __famfs_fuse_filemap_fault(vmf, 0, true); +} + +const struct vm_operations_struct famfs_file_vm_ops = { + .fault = famfs_filemap_fault, + .huge_fault = famfs_filemap_huge_fault, + .map_pages = filemap_map_pages, + .page_mkwrite = famfs_filemap_mkwrite, + .pfn_mkwrite = famfs_filemap_mkwrite, +}; + +/********************************************************************* + * file_operations + */ + +/** + * famfs_file_bad() - Check for files that aren't in a valid state + * + * @inode: inode + * + * Returns: 0=success + * -errno=failure + */ +static int +famfs_file_bad(struct inode *inode) +{ + struct fuse_inode *fi = get_fuse_inode(inode); + struct famfs_file_meta *meta = fi->famfs_meta; + size_t i_size = i_size_read(inode); + + if (!meta) { + pr_err("%s: un-initialized famfs file\n", __func__); + return -EIO; + } + if (meta->error) { + pr_debug("%s: previously detected metadata errors\n", __func__); + return -EIO; + } + if (i_size != meta->file_size) { + pr_warn("%s: i_size overwritten from %ld to %ld\n", + __func__, meta->file_size, i_size); + meta->error = true; + return -ENXIO; + } + if (!IS_DAX(inode)) { + pr_debug("%s: inode %llx IS_DAX is false\n", + __func__, (u64)inode); + return -ENXIO; + } + return 0; +} + +static ssize_t +famfs_fuse_rw_prep(struct kiocb *iocb, struct iov_iter *ubuf) +{ + struct inode *inode = iocb->ki_filp->f_mapping->host; + size_t i_size = i_size_read(inode); + size_t count = iov_iter_count(ubuf); + size_t max_count; + ssize_t rc; + + rc = famfs_file_bad(inode); + if (rc) + return (ssize_t)rc; + + /* Avoid unsigned underflow if position is past EOF */ + if (iocb->ki_pos >= i_size) + max_count = 0; + else + max_count = i_size - iocb->ki_pos; + + if (count > max_count) + iov_iter_truncate(ubuf, max_count); + + if (!iov_iter_count(ubuf)) + return 0; + + return rc; +} + +ssize_t +famfs_fuse_read_iter(struct kiocb *iocb, struct iov_iter *to) +{ + ssize_t rc; + + rc = famfs_fuse_rw_prep(iocb, to); + if (rc) + return rc; + + if (!iov_iter_count(to)) + return 0; + + rc = dax_iomap_rw(iocb, to, &famfs_iomap_ops); + + file_accessed(iocb->ki_filp); + return rc; +} + +ssize_t +famfs_fuse_write_iter(struct kiocb *iocb, struct iov_iter *from) +{ + ssize_t rc; + + rc = famfs_fuse_rw_prep(iocb, from); + if (rc) + return rc; + + if (!iov_iter_count(from)) + return 0; + + return dax_iomap_rw(iocb, from, &famfs_iomap_ops); +} + +int +famfs_fuse_mmap(struct file *file, struct vm_area_struct *vma) +{ + struct inode *inode = file_inode(file); + ssize_t rc; + + rc = famfs_file_bad(inode); + if (rc) + return rc; + + file_accessed(file); + vma->vm_ops = &famfs_file_vm_ops; + vm_flags_set(vma, VM_HUGEPAGE); + return 0; +} #define FMAP_BUFSIZE_INIT PAGE_SIZE /* diff --git a/fs/fuse/file.c b/fs/fuse/file.c index b4e7b6a64587..2435a79cbb4a 100644 --- a/fs/fuse/file.c +++ b/fs/fuse/file.c @@ -1859,6 +1859,8 @@ static ssize_t fuse_file_read_iter(struct kiocb *iocb, struct iov_iter *to) if (FUSE_IS_VIRTIO_DAX(fi)) return fuse_dax_read_iter(iocb, to); + if (fuse_file_famfs(fi)) + return famfs_fuse_read_iter(iocb, to); /* FOPEN_DIRECT_IO overrides FOPEN_PASSTHROUGH */ if (ff->open_flags & FOPEN_DIRECT_IO) @@ -1881,6 +1883,8 @@ static ssize_t fuse_file_write_iter(struct kiocb *iocb, struct iov_iter *from) if (FUSE_IS_VIRTIO_DAX(fi)) return fuse_dax_write_iter(iocb, from); + if (fuse_file_famfs(fi)) + return famfs_fuse_write_iter(iocb, from); /* FOPEN_DIRECT_IO overrides FOPEN_PASSTHROUGH */ if (ff->open_flags & FOPEN_DIRECT_IO) @@ -1896,9 +1900,13 @@ static ssize_t fuse_splice_read(struct file *in, loff_t *ppos, unsigned int flags) { struct fuse_file *ff = in->private_data; + struct inode *inode = file_inode(in); + struct fuse_inode *fi = get_fuse_inode(inode); /* FOPEN_DIRECT_IO overrides FOPEN_PASSTHROUGH */ - if (fuse_file_passthrough(ff) && !(ff->open_flags & FOPEN_DIRECT_IO)) + if (fuse_file_famfs(fi)) + return -EIO; /* famfs does not use the page cache... */ + else if (fuse_file_passthrough(ff) && !(ff->open_flags & FOPEN_DIRECT_IO)) return fuse_passthrough_splice_read(in, ppos, pipe, len, flags); else return filemap_splice_read(in, ppos, pipe, len, flags); @@ -1908,9 +1916,13 @@ static ssize_t fuse_splice_write(struct pipe_inode_info *pipe, struct file *out, loff_t *ppos, size_t len, unsigned int flags) { struct fuse_file *ff = out->private_data; + struct inode *inode = file_inode(out); + struct fuse_inode *fi = get_fuse_inode(inode); /* FOPEN_DIRECT_IO overrides FOPEN_PASSTHROUGH */ - if (fuse_file_passthrough(ff) && !(ff->open_flags & FOPEN_DIRECT_IO)) + if (fuse_file_famfs(fi)) + return -EIO; /* famfs does not use the page cache... */ + else if (fuse_file_passthrough(ff) && !(ff->open_flags & FOPEN_DIRECT_IO)) return fuse_passthrough_splice_write(pipe, out, ppos, len, flags); else return iter_file_splice_write(pipe, out, ppos, len, flags); @@ -2420,6 +2432,8 @@ static int fuse_file_mmap(struct file *file, struct vm_area_struct *vma) /* DAX mmap is superior to direct_io mmap */ if (FUSE_IS_VIRTIO_DAX(fi)) return fuse_dax_mmap(file, vma); + if (fuse_file_famfs(fi)) + return famfs_fuse_mmap(file, vma); /* * If inode is in passthrough io mode, because it has some file open diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h index 5394aae9dbac..7281fb8b6402 100644 --- a/fs/fuse/fuse_i.h +++ b/fs/fuse/fuse_i.h @@ -1355,6 +1355,9 @@ extern void fuse_sysctl_unregister(void); int famfs_file_init_dax(struct fuse_mount *fm, struct inode *inode, void *fmap_buf, size_t fmap_size); +ssize_t famfs_fuse_write_iter(struct kiocb *iocb, struct iov_iter *from); +ssize_t famfs_fuse_read_iter(struct kiocb *iocb, struct iov_iter *to); +int famfs_fuse_mmap(struct file *file, struct vm_area_struct *vma); void __famfs_meta_free(void *map); void famfs_teardown(struct fuse_conn *fc); @@ -1400,6 +1403,22 @@ static inline void famfs_teardown(struct fuse_conn *fc) { } +static inline ssize_t famfs_fuse_write_iter(struct kiocb *iocb, + struct iov_iter *to) +{ + return -ENODEV; +} +static inline ssize_t famfs_fuse_read_iter(struct kiocb *iocb, + struct iov_iter *to) +{ + return -ENODEV; +} +static inline int famfs_fuse_mmap(struct file *file, + struct vm_area_struct *vma) +{ + return -ENODEV; +} + static inline struct fuse_backing *famfs_meta_set(struct fuse_inode *fi, void *meta) { -- 2.53.0
