diff options
Diffstat (limited to 'fs/read_write.c')
| -rw-r--r-- | fs/read_write.c | 204 |
1 files changed, 204 insertions, 0 deletions
diff --git a/fs/read_write.c b/fs/read_write.c index 6674a4b83c54..dbf3f7ffdf3f 100644 --- a/fs/read_write.c +++ b/fs/read_write.c @@ -1667,6 +1667,114 @@ static int clone_verify_area(struct file *file, loff_t pos, u64 len, bool write) return security_file_permission(file, write ? MAY_WRITE : MAY_READ); } +/* + * Check that the two inodes are eligible for cloning, the ranges make + * sense, and then flush all dirty data. Caller must ensure that the + * inodes have been locked against any other modifications. + */ +int vfs_clone_file_prep_inodes(struct inode *inode_in, loff_t pos_in, + struct inode *inode_out, loff_t pos_out, + u64 *len, bool is_dedupe) +{ + loff_t bs = inode_out->i_sb->s_blocksize; + loff_t blen; + loff_t isize; + bool same_inode = (inode_in == inode_out); + int ret; + + /* Don't touch certain kinds of inodes */ + if (IS_IMMUTABLE(inode_out)) + return -EPERM; + + if (IS_SWAPFILE(inode_in) || IS_SWAPFILE(inode_out)) + return -ETXTBSY; + + /* Don't reflink dirs, pipes, sockets... */ + if (S_ISDIR(inode_in->i_mode) || S_ISDIR(inode_out->i_mode)) + return -EISDIR; + if (!S_ISREG(inode_in->i_mode) || !S_ISREG(inode_out->i_mode)) + return -EINVAL; + + /* Are we going all the way to the end? */ + isize = i_size_read(inode_in); + if (isize == 0) { + *len = 0; + return 0; + } + + /* Zero length dedupe exits immediately; reflink goes to EOF. */ + if (*len == 0) { + if (is_dedupe) { + *len = 0; + return 0; + } + *len = isize - pos_in; + } + + /* Ensure offsets don't wrap and the input is inside i_size */ + if (pos_in + *len < pos_in || pos_out + *len < pos_out || + pos_in + *len > isize) + return -EINVAL; + + /* Don't allow dedupe past EOF in the dest file */ + if (is_dedupe) { + loff_t disize; + + disize = i_size_read(inode_out); + if (pos_out >= disize || pos_out + *len > disize) + return -EINVAL; + } + + /* If we're linking to EOF, continue to the block boundary. */ + if (pos_in + *len == isize) + blen = ALIGN(isize, bs) - pos_in; + else + blen = *len; + + /* Only reflink if we're aligned to block boundaries */ + if (!IS_ALIGNED(pos_in, bs) || !IS_ALIGNED(pos_in + blen, bs) || + !IS_ALIGNED(pos_out, bs) || !IS_ALIGNED(pos_out + blen, bs)) + return -EINVAL; + + /* Don't allow overlapped reflink within the same file */ + if (same_inode) { + if (pos_out + blen > pos_in && pos_out < pos_in + blen) + return -EINVAL; + } + + /* Wait for the completion of any pending IOs on both files */ + inode_dio_wait(inode_in); + if (!same_inode) + inode_dio_wait(inode_out); + + ret = filemap_write_and_wait_range(inode_in->i_mapping, + pos_in, pos_in + *len - 1); + if (ret) + return ret; + + ret = filemap_write_and_wait_range(inode_out->i_mapping, + pos_out, pos_out + *len - 1); + if (ret) + return ret; + + /* + * Check that the extents are the same. + */ + if (is_dedupe) { + bool is_same = false; + + ret = vfs_dedupe_file_range_compare(inode_in, pos_in, + inode_out, pos_out, *len, &is_same); + if (ret) + return ret; + if (!is_same) + return -EBADE; + } + + return 0; +} +EXPORT_SYMBOL(vfs_clone_file_prep_inodes); + int vfs_clone_file_range(struct file *file_in, loff_t pos_in, struct file *file_out, loff_t pos_out, u64 len) { @@ -1718,6 +1826,102 @@ int vfs_clone_file_range(struct file *file_in, loff_t pos_in, } EXPORT_SYMBOL(vfs_clone_file_range); +/* + * Read a page's worth of file data into the page cache. Return the page + * locked. + */ +static struct page *vfs_dedupe_get_page(struct inode *inode, loff_t offset) +{ + struct address_space *mapping; + struct page *page; + pgoff_t n; + + n = offset >> PAGE_SHIFT; + mapping = inode->i_mapping; + page = read_mapping_page(mapping, n, NULL); + if (IS_ERR(page)) + return page; + if (!PageUptodate(page)) { + put_page(page); + return ERR_PTR(-EIO); + } + lock_page(page); + return page; +} + +/* + * Compare extents of two files to see if they are the same. + * Caller must have locked both inodes to prevent write races. + */ +int vfs_dedupe_file_range_compare(struct inode *src, loff_t srcoff, + struct inode *dest, loff_t destoff, + loff_t len, bool *is_same) +{ + loff_t src_poff; + loff_t dest_poff; + void *src_addr; + void *dest_addr; + struct page *src_page; + struct page *dest_page; + loff_t cmp_len; + bool same; + int error; + + error = -EINVAL; + same = true; + while (len) { + src_poff = srcoff & (PAGE_SIZE - 1); + dest_poff = destoff & (PAGE_SIZE - 1); + cmp_len = min(PAGE_SIZE - src_poff, + PAGE_SIZE - dest_poff); + cmp_len = min(cmp_len, len); + if (cmp_len <= 0) + goto out_error; + + src_page = vfs_dedupe_get_page(src, srcoff); + if (IS_ERR(src_page)) { + error = PTR_ERR(src_page); + goto out_error; + } + dest_page = vfs_dedupe_get_page(dest, destoff); + if (IS_ERR(dest_page)) { + error = PTR_ERR(dest_page); + unlock_page(src_page); + put_page(src_page); + goto out_error; + } + src_addr = kmap_atomic(src_page); + dest_addr = kmap_atomic(dest_page); + + flush_dcache_page(src_page); + flush_dcache_page(dest_page); + + if (memcmp(src_addr + src_poff, dest_addr + dest_poff, cmp_len)) + same = false; + + kunmap_atomic(dest_addr); + kunmap_atomic(src_addr); + unlock_page(dest_page); + unlock_page(src_page); + put_page(dest_page); + put_page(src_page); + + if (!same) + break; + + srcoff += cmp_len; + destoff += cmp_len; + len -= cmp_len; + } + + *is_same = same; + return 0; + +out_error: + return error; +} +EXPORT_SYMBOL(vfs_dedupe_file_range_compare); + int vfs_dedupe_file_range(struct file *file, struct file_dedupe_range *same) { struct file_dedupe_range_info *info; |