btrfs: enhance compression error messages

Add more verbose and specific messages to all main error points in
compression code for all algorithms. Currently there's no way to know
which inode is affected or where in the data errors happened.

The messages follow a common format:

- what happened
- error code if relevant
- root and inode
- additional data like offsets or lengths

There's no helper for the messages as they differ in some details and
that would be cumbersome to generalize to a single function. As all the
errors are "almost never happens" there are the unlikely annotations
done as compression is hot path.

Signed-off-by: David Sterba <dsterba@suse.com>

1 files changed, 30 insertions, 13 deletions

diff --git a/fs/btrfs/lzo.c b/fs/btrfs/lzo.c
index 1c396ac167aa..1e2a68b8f62d 100644
--- a/fs/btrfs/lzo.c
+++ b/fs/btrfs/lzo.c
@@ -258,8 +258,8 @@ int lzo_compress_folios(struct list_head *ws, struct address_space *mapping,
 				       workspace->cbuf, &out_len,
 				       workspace->mem);
 		kunmap_local(data_in);
-		if (ret < 0) {
-			pr_debug("BTRFS: lzo in loop returned %d\n", ret);
+		if (unlikely(ret < 0)) {
+			/* lzo1x_1_compress never fails. */
 			ret = -EIO;
 			goto out;
 		}
@@ -354,11 +354,14 @@ int lzo_decompress_bio(struct list_head *ws, struct compressed_bio *cb)
 	 * and all sectors should be used.
 	 * If this happens, it means the compressed extent is corrupted.
 	 */
-	if (len_in > min_t(size_t, BTRFS_MAX_COMPRESSED, cb->compressed_len) ||
-	    round_up(len_in, sectorsize) < cb->compressed_len) {
+	if (unlikely(len_in > min_t(size_t, BTRFS_MAX_COMPRESSED, cb->compressed_len) ||
+		     round_up(len_in, sectorsize) < cb->compressed_len)) {
+		struct btrfs_inode *inode = cb->bbio.inode;
+
 		btrfs_err(fs_info,
-			"invalid lzo header, lzo len %u compressed len %u",
-			len_in, cb->compressed_len);
+"lzo header invalid, root %llu inode %llu offset %llu lzo len %u compressed len %u",
+			  btrfs_root_id(inode->root), btrfs_ino(inode),
+			  cb->start, len_in, cb->compressed_len);
 		return -EUCLEAN;
 	}
 
@@ -383,13 +386,17 @@ int lzo_decompress_bio(struct list_head *ws, struct compressed_bio *cb)
 		kunmap_local(kaddr);
 		cur_in += LZO_LEN;
 
-		if (seg_len > WORKSPACE_CBUF_LENGTH) {
+		if (unlikely(seg_len > WORKSPACE_CBUF_LENGTH)) {
+			struct btrfs_inode *inode = cb->bbio.inode;
+
 			/*
 			 * seg_len shouldn't be larger than we have allocated
 			 * for workspace->cbuf
 			 */
-			btrfs_err(fs_info, "unexpectedly large lzo segment len %u",
-					seg_len);
+			btrfs_err(fs_info,
+			"lzo segment too big, root %llu inode %llu offset %llu len %u",
+				  btrfs_root_id(inode->root), btrfs_ino(inode),
+				  cb->start, seg_len);
 			return -EIO;
 		}
 
@@ -399,8 +406,13 @@ int lzo_decompress_bio(struct list_head *ws, struct compressed_bio *cb)
 		/* Decompress the data */
 		ret = lzo1x_decompress_safe(workspace->cbuf, seg_len,
 					    workspace->buf, &out_len);
-		if (ret != LZO_E_OK) {
-			btrfs_err(fs_info, "failed to decompress");
+		if (unlikely(ret != LZO_E_OK)) {
+			struct btrfs_inode *inode = cb->bbio.inode;
+
+			btrfs_err(fs_info,
+		"lzo decompression failed, error %d root %llu inode %llu offset %llu",
+				  ret, btrfs_root_id(inode->root), btrfs_ino(inode),
+				  cb->start);
 			return -EIO;
 		}
 
@@ -454,8 +466,13 @@ int lzo_decompress(struct list_head *ws, const u8 *data_in,
 
 	out_len = sectorsize;
 	ret = lzo1x_decompress_safe(data_in, in_len, workspace->buf, &out_len);
-	if (ret != LZO_E_OK) {
-		pr_warn("BTRFS: decompress failed!\n");
+	if (unlikely(ret != LZO_E_OK)) {
+		struct btrfs_inode *inode = BTRFS_I(dest_page->mapping->host);
+
+		btrfs_err(fs_info,
+		"lzo decompression failed, error %d root %llu inode %llu offset %llu",
+			  ret, btrfs_root_id(inode->root), btrfs_ino(inode),
+			  page_offset(dest_page));
 		ret = -EIO;
 		goto out;
 	}