diff options
Diffstat (limited to 'fs/dax.c')
| -rw-r--r-- | fs/dax.c | 252 |
1 files changed, 240 insertions, 12 deletions
@@ -31,6 +31,8 @@ #include <linux/vmstat.h> #include <linux/pfn_t.h> #include <linux/sizes.h> +#include <linux/iomap.h> +#include "internal.h" /* * We use lowest available bit in exceptional entry for locking, other two @@ -580,14 +582,13 @@ static int dax_load_hole(struct address_space *mapping, void *entry, return VM_FAULT_LOCKED; } -static int copy_user_bh(struct page *to, struct inode *inode, - struct buffer_head *bh, unsigned long vaddr) +static int copy_user_dax(struct block_device *bdev, sector_t sector, size_t size, + struct page *to, unsigned long vaddr) { struct blk_dax_ctl dax = { - .sector = to_sector(bh, inode), - .size = bh->b_size, + .sector = sector, + .size = size, }; - struct block_device *bdev = bh->b_bdev; void *vto; if (dax_map_atomic(bdev, &dax) < 0) @@ -790,14 +791,13 @@ int dax_writeback_mapping_range(struct address_space *mapping, EXPORT_SYMBOL_GPL(dax_writeback_mapping_range); static int dax_insert_mapping(struct address_space *mapping, - struct buffer_head *bh, void **entryp, - struct vm_area_struct *vma, struct vm_fault *vmf) + struct block_device *bdev, sector_t sector, size_t size, + void **entryp, struct vm_area_struct *vma, struct vm_fault *vmf) { unsigned long vaddr = (unsigned long)vmf->virtual_address; - struct block_device *bdev = bh->b_bdev; struct blk_dax_ctl dax = { - .sector = to_sector(bh, mapping->host), - .size = bh->b_size, + .sector = sector, + .size = size, }; void *ret; void *entry = *entryp; @@ -868,7 +868,8 @@ int dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf, if (vmf->cow_page) { struct page *new_page = vmf->cow_page; if (buffer_written(&bh)) - error = copy_user_bh(new_page, inode, &bh, vaddr); + error = copy_user_dax(bh.b_bdev, to_sector(&bh, inode), + bh.b_size, new_page, vaddr); else clear_user_highpage(new_page, vaddr); if (error) @@ -898,7 +899,8 @@ int dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf, /* Filesystem should not return unwritten buffers to us! */ WARN_ON_ONCE(buffer_unwritten(&bh) || buffer_new(&bh)); - error = dax_insert_mapping(mapping, &bh, &entry, vma, vmf); + error = dax_insert_mapping(mapping, bh.b_bdev, to_sector(&bh, inode), + bh.b_size, &entry, vma, vmf); unlock_entry: put_locked_mapping_entry(mapping, vmf->pgoff, entry); out: @@ -1241,3 +1243,229 @@ int dax_truncate_page(struct inode *inode, loff_t from, get_block_t get_block) return dax_zero_page_range(inode, from, length, get_block); } EXPORT_SYMBOL_GPL(dax_truncate_page); + +#ifdef CONFIG_FS_IOMAP +static loff_t +iomap_dax_actor(struct inode *inode, loff_t pos, loff_t length, void *data, + struct iomap *iomap) +{ + struct iov_iter *iter = data; + loff_t end = pos + length, done = 0; + ssize_t ret = 0; + + if (iov_iter_rw(iter) == READ) { + end = min(end, i_size_read(inode)); + if (pos >= end) + return 0; + + if (iomap->type == IOMAP_HOLE || iomap->type == IOMAP_UNWRITTEN) + return iov_iter_zero(min(length, end - pos), iter); + } + + if (WARN_ON_ONCE(iomap->type != IOMAP_MAPPED)) + return -EIO; + + while (pos < end) { + unsigned offset = pos & (PAGE_SIZE - 1); + struct blk_dax_ctl dax = { 0 }; + ssize_t map_len; + + dax.sector = iomap->blkno + + (((pos & PAGE_MASK) - iomap->offset) >> 9); + dax.size = (length + offset + PAGE_SIZE - 1) & PAGE_MASK; + map_len = dax_map_atomic(iomap->bdev, &dax); + if (map_len < 0) { + ret = map_len; + break; + } + + dax.addr += offset; + map_len -= offset; + if (map_len > end - pos) + map_len = end - pos; + + if (iov_iter_rw(iter) == WRITE) + map_len = copy_from_iter_pmem(dax.addr, map_len, iter); + else + map_len = copy_to_iter(dax.addr, map_len, iter); + dax_unmap_atomic(iomap->bdev, &dax); + if (map_len <= 0) { + ret = map_len ? map_len : -EFAULT; + break; + } + + pos += map_len; + length -= map_len; + done += map_len; + } + + return done ? done : ret; +} + +/** + * iomap_dax_rw - Perform I/O to a DAX file + * @iocb: The control block for this I/O + * @iter: The addresses to do I/O from or to + * @ops: iomap ops passed from the file system + * + * This function performs read and write operations to directly mapped + * persistent memory. The callers needs to take care of read/write exclusion + * and evicting any page cache pages in the region under I/O. + */ +ssize_t +iomap_dax_rw(struct kiocb *iocb, struct iov_iter *iter, + struct iomap_ops *ops) +{ + struct address_space *mapping = iocb->ki_filp->f_mapping; + struct inode *inode = mapping->host; + loff_t pos = iocb->ki_pos, ret = 0, done = 0; + unsigned flags = 0; + + if (iov_iter_rw(iter) == WRITE) + flags |= IOMAP_WRITE; + + /* + * Yes, even DAX files can have page cache attached to them: A zeroed + * page is inserted into the pagecache when we have to serve a write + * fault on a hole. It should never be dirtied and can simply be + * dropped from the pagecache once we get real data for the page. + * + * XXX: This is racy against mmap, and there's nothing we can do about + * it. We'll eventually need to shift this down even further so that + * we can check if we allocated blocks over a hole first. + */ + if (mapping->nrpages) { + ret = invalidate_inode_pages2_range(mapping, + pos >> PAGE_SHIFT, + (pos + iov_iter_count(iter) - 1) >> PAGE_SHIFT); + WARN_ON_ONCE(ret); + } + + while (iov_iter_count(iter)) { + ret = iomap_apply(inode, pos, iov_iter_count(iter), flags, ops, + iter, iomap_dax_actor); + if (ret <= 0) + break; + pos += ret; + done += ret; + } + + iocb->ki_pos += done; + return done ? done : ret; +} +EXPORT_SYMBOL_GPL(iomap_dax_rw); + +/** + * iomap_dax_fault - handle a page fault on a DAX file + * @vma: The virtual memory area where the fault occurred + * @vmf: The description of the fault + * @ops: iomap ops passed from the file system + * + * When a page fault occurs, filesystems may call this helper in their fault + * or mkwrite handler for DAX files. Assumes the caller has done all the + * necessary locking for the page fault to proceed successfully. + */ +int iomap_dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf, + struct iomap_ops *ops) +{ + struct address_space *mapping = vma->vm_file->f_mapping; + struct inode *inode = mapping->host; + unsigned long vaddr = (unsigned long)vmf->virtual_address; + loff_t pos = (loff_t)vmf->pgoff << PAGE_SHIFT; + sector_t sector; + struct iomap iomap = { 0 }; + unsigned flags = 0; + int error, major = 0; + void *entry; + + /* + * Check whether offset isn't beyond end of file now. Caller is supposed + * to hold locks serializing us with truncate / punch hole so this is + * a reliable test. + */ + if (pos >= i_size_read(inode)) + return VM_FAULT_SIGBUS; + + entry = grab_mapping_entry(mapping, vmf->pgoff); + if (IS_ERR(entry)) { + error = PTR_ERR(entry); + goto out; + } + + if ((vmf->flags & FAULT_FLAG_WRITE) && !vmf->cow_page) + flags |= IOMAP_WRITE; + + /* + * Note that we don't bother to use iomap_apply here: DAX required + * the file system block size to be equal the page size, which means + * that we never have to deal with more than a single extent here. + */ + error = ops->iomap_begin(inode, pos, PAGE_SIZE, flags, &iomap); + if (error) + goto unlock_entry; + if (WARN_ON_ONCE(iomap.offset + iomap.length < pos + PAGE_SIZE)) { + error = -EIO; /* fs corruption? */ + goto unlock_entry; + } + + sector = iomap.blkno + (((pos & PAGE_MASK) - iomap.offset) >> 9); + + if (vmf->cow_page) { + switch (iomap.type) { + case IOMAP_HOLE: + case IOMAP_UNWRITTEN: + clear_user_highpage(vmf->cow_page, vaddr); + break; + case IOMAP_MAPPED: + error = copy_user_dax(iomap.bdev, sector, PAGE_SIZE, + vmf->cow_page, vaddr); + break; + default: + WARN_ON_ONCE(1); + error = -EIO; + break; + } + + if (error) + goto unlock_entry; + if (!radix_tree_exceptional_entry(entry)) { + vmf->page = entry; + return VM_FAULT_LOCKED; + } + vmf->entry = entry; + return VM_FAULT_DAX_LOCKED; + } + + switch (iomap.type) { + case IOMAP_MAPPED: + if (iomap.flags & IOMAP_F_NEW) { + count_vm_event(PGMAJFAULT); + mem_cgroup_count_vm_event(vma->vm_mm, PGMAJFAULT); + major = VM_FAULT_MAJOR; + } + error = dax_insert_mapping(mapping, iomap.bdev, sector, + PAGE_SIZE, &entry, vma, vmf); + break; + case IOMAP_UNWRITTEN: + case IOMAP_HOLE: + if (!(vmf->flags & FAULT_FLAG_WRITE)) + return dax_load_hole(mapping, entry, vmf); + /*FALLTHRU*/ + default: + WARN_ON_ONCE(1); + error = -EIO; + break; + } + + unlock_entry: + put_locked_mapping_entry(mapping, vmf->pgoff, entry); + out: + if (error == -ENOMEM) + return VM_FAULT_OOM | major; + /* -EBUSY is fine, somebody else faulted on the same PTE */ + if (error < 0 && error != -EBUSY) + return VM_FAULT_SIGBUS | major; + return VM_FAULT_NOPAGE | major; +} +EXPORT_SYMBOL_GPL(iomap_dax_fault); +#endif /* CONFIG_FS_IOMAP */ |