btrfs-progs: check read extent errors when mapping

coverity barked out a warning that btrfs-map-logical was storing but
ignoring errors from read_extent_from_disk().   So don't ignore 'em.  I
made extent reading errors fatal to match the fatal errors from mapping
mirrors above.

And while we're at it have read_extent_from_disk() return -errno pread
errors instead of -EIO or -1 (-EPERM).  The only other caller who tests
errors clobbers them with -EIO.

Signed-off-by: Zach Brown <zab@zabbo.net>
Signed-off-by: David Sterba <dsterba@suse.cz>

diff --git a/btrfs-map-logical.c b/btrfs-map-logical.c
index 6b475fc..47d1104 100644 (file)
--- a/btrfs-map-logical.c
+++ b/btrfs-map-logical.c
@@ -76,8 +76,18 @@ static struct extent_buffer * debug_read_block(struct btrfs_root *root,
                        (unsigned long long)eb->dev_bytenr, device->name);
                kfree(multi);
 
-               if (!copy || mirror_num == copy)
+               if (!copy || mirror_num == copy) {
                        ret = read_extent_from_disk(eb, 0, eb->len);
+                       if (ret) {
+                               fprintf(info_file,
+                                       "Error: failed to read extent: mirror %d logical %llu: %s\n",
+                                       mirror_num, (unsigned long long)eb->start,
+                                       strerror(-ret));
+                               free_extent_buffer(eb);
+                               eb = NULL;
+                               break;
+                       }
+               }
 
                num_copies = btrfs_num_copies(&root->fs_info->mapping_tree,
                                              eb->start, eb->len);

diff --git a/extent_io.c b/extent_io.c
index de9e0ec..9c982f9 100644 (file)
--- a/extent_io.c
+++ b/extent_io.c
@@ -666,8 +666,10 @@ int read_extent_from_disk(struct extent_buffer *eb,
 {
        int ret;
        ret = pread(eb->fd, eb->data + offset, len, eb->dev_bytenr);
-       if (ret < 0)
+       if (ret < 0) {
+               ret = -errno;
                goto out;
+       }
        if (ret != len) {
                ret = -EIO;
                goto out;