[RFC PATCH v10 44/48] ceph: plumb in decryption during sync reads

[Jeff Layton <jlayton@kernel.org>]

Note that the crypto block may be smaller than a page, but the reverse
cannot be true.

Signed-off-by: Jeff Layton <jlayton@kernel.org>
---
 fs/ceph/file.c | 94 ++++++++++++++++++++++++++++++++++++--------------
 1 file changed, 69 insertions(+), 25 deletions(-)

diff --git a/fs/ceph/file.c b/fs/ceph/file.c
index 41766b2012e9..b4f2fcd33837 100644
--- a/fs/ceph/file.c
+++ b/fs/ceph/file.c
@@ -926,9 +926,17 @@ ssize_t __ceph_sync_read(struct inode *inode, loff_t *ki_pos,
 		bool more;
 		int idx;
 		size_t left;
+		u64 read_off = off;
+		u64 read_len = len;
+
+		/* determine new offset/length if encrypted */
+		fscrypt_adjust_off_and_len(inode, &read_off, &read_len);
+
+		dout("sync_read orig %llu~%llu reading %llu~%llu",
+		     off, len, read_off, read_len);
 
 		req = ceph_osdc_new_request(osdc, &ci->i_layout,
-					ci->i_vino, off, &len, 0, 1,
+					ci->i_vino, read_off, &read_len, 0, 1,
 					CEPH_OSD_OP_READ, CEPH_OSD_FLAG_READ,
 					NULL, ci->i_truncate_seq,
 					ci->i_truncate_size, false);
@@ -937,10 +945,13 @@ ssize_t __ceph_sync_read(struct inode *inode, loff_t *ki_pos,
 			break;
 		}
 
+		/* adjust len downward if the request truncated the len */
+		if (off + len > read_off + read_len)
+			len = read_off + read_len - off;
 		more = len < iov_iter_count(to);
 
-		num_pages = calc_pages_for(off, len);
-		page_off = off & ~PAGE_MASK;
+		num_pages = calc_pages_for(read_off, read_len);
+		page_off = offset_in_page(off);
 		pages = ceph_alloc_page_vector(num_pages, GFP_KERNEL);
 		if (IS_ERR(pages)) {
 			ceph_osdc_put_request(req);
@@ -948,7 +959,8 @@ ssize_t __ceph_sync_read(struct inode *inode, loff_t *ki_pos,
 			break;
 		}
 
-		osd_req_op_extent_osd_data_pages(req, 0, pages, len, page_off,
+		osd_req_op_extent_osd_data_pages(req, 0, pages, read_len,
+						 offset_in_page(read_off),
 						 false, false);
 		ret = ceph_osdc_start_request(osdc, req, false);
 		if (!ret)
@@ -957,23 +969,50 @@ ssize_t __ceph_sync_read(struct inode *inode, loff_t *ki_pos,
 		ceph_update_read_metrics(&fsc->mdsc->metric,
 					 req->r_start_latency,
 					 req->r_end_latency,
-					 len, ret);
+					 read_len, ret);
 
 		if (ret > 0)
 			objver = req->r_version;
 		ceph_osdc_put_request(req);
-
 		i_size = i_size_read(inode);
 		dout("sync_read %llu~%llu got %zd i_size %llu%s\n",
 		     off, len, ret, i_size, (more ? " MORE" : ""));
 
-		if (ret == -ENOENT)
+		if (ret == -ENOENT) {
+			/* No object? Then this is a hole */
 			ret = 0;
+		} else if (ret > 0 && IS_ENCRYPTED(inode)) {
+			int fret;
+
+			fret = ceph_fscrypt_decrypt_pages(inode, pages, read_off, ret);
+			if (fret < 0) {
+				ceph_release_page_vector(pages, num_pages);
+				ret = fret;
+				break;
+			}
+
+			dout("sync_read decrypted fret %d\n", fret);
+
+			/* account for any partial block at the beginning */
+			fret -= (off - read_off);
+
+			/*
+			 * Short read after big offset adjustment?
+			 * Nothing is usable, just call it a zero
+			 * len read.
+			 */
+			fret = max(fret, 0);
+
+			/* account for partial block at the end */
+			ret = min_t(ssize_t, fret, len);
+		}
+
+		/* Short read but not EOF? Zero out the remainder. */
 		if (ret >= 0 && ret < len && (off + ret < i_size)) {
 			int zlen = min(len - ret, i_size - off - ret);
 			int zoff = page_off + ret;
 			dout("sync_read zero gap %llu~%llu\n",
-                             off + ret, off + ret + zlen);
+			     off + ret, off + ret + zlen);
 			ceph_zero_page_vector_range(zoff, zlen, pages);
 			ret += zlen;
 		}
@@ -981,15 +1020,15 @@ ssize_t __ceph_sync_read(struct inode *inode, loff_t *ki_pos,
 		idx = 0;
 		left = ret > 0 ? ret : 0;
 		while (left > 0) {
-			size_t len, copied;
-			page_off = off & ~PAGE_MASK;
-			len = min_t(size_t, left, PAGE_SIZE - page_off);
+			size_t plen, copied;
+			plen = min_t(size_t, left, PAGE_SIZE - page_off);
 			SetPageUptodate(pages[idx]);
 			copied = copy_page_to_iter(pages[idx++],
-						   page_off, len, to);
+						   page_off, plen, to);
 			off += copied;
 			left -= copied;
-			if (copied < len) {
+			page_off = 0;
+			if (copied < plen) {
 				ret = -EFAULT;
 				break;
 			}
@@ -1006,20 +1045,21 @@ ssize_t __ceph_sync_read(struct inode *inode, loff_t *ki_pos,
 			break;
 	}
 
-	if (off > *ki_pos) {
-		if (off >= i_size) {
-			*retry_op = CHECK_EOF;
-			ret = i_size - *ki_pos;
-			*ki_pos = i_size;
-		} else {
-			ret = off - *ki_pos;
-			*ki_pos = off;
+	if (ret > 0) {
+		if (off > *ki_pos) {
+			if (off >= i_size) {
+				*retry_op = CHECK_EOF;
+				ret = i_size - *ki_pos;
+				*ki_pos = i_size;
+			} else {
+				ret = off - *ki_pos;
+				*ki_pos = off;
+			}
 		}
-	}
-
-	if (last_objver && ret > 0)
-		*last_objver = objver;
 
+		if (last_objver)
+			*last_objver = objver;
+	}
 	dout("sync_read result %zd retry_op %d\n", ret, *retry_op);
 	return ret;
 }
@@ -1532,6 +1572,9 @@ ceph_sync_write(struct kiocb *iocb, struct iov_iter *from, loff_t pos,
 		last = (pos + len) != (write_pos + write_len);
 		rmw = first || last;
 
+		dout("sync_write ino %llx %lld~%llu adjusted %lld~%llu -- %srmw\n",
+		     ci->i_vino.ino, pos, len, write_pos, write_len, rmw ? "" : "no ");
+
 		/*
 		 * The data is emplaced into the page as it would be if it were in
 		 * an array of pagecache pages.
@@ -1761,6 +1804,7 @@ ceph_sync_write(struct kiocb *iocb, struct iov_iter *from, loff_t pos,
 		ceph_clear_error_write(ci);
 		pos += len;
 		written += len;
+		dout("sync_write written %d\n", written);
 		if (pos > i_size_read(inode)) {
 			check_caps = ceph_inode_set_size(inode, pos);
 			if (check_caps)
-- 
2.34.1