diff options
Diffstat (limited to 'fs/dax.c')
| -rw-r--r-- | fs/dax.c | 114 |
1 files changed, 114 insertions, 0 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 @@ -1241,3 +1243,115 @@ 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); +#endif /* CONFIG_FS_IOMAP */ |