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btrfs-progs: Use existing facility to replace read_data_extent function 

Function read_data_extent() in btrfs-image.c is using manual-and-read
codes.
Replace it with existing read_extent_data() to reduce duplication.

Also, now we can use other mirror to try our best to do the dump, just
like read_tree_block().

Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
Signed-off-by: David Sterba <dsterba@suse.com>
master
Qu Wenruo 2015-08-21 11:21:27 +08:00 committed by David Sterba
parent 59df5b6e9a
commit 2d46558b30
1 changed files with 20 additions and 40 deletions
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60
btrfs-image.c
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@ -872,54 +872,34 @@ out:
static int read_data_extent(struct metadump_struct *md,
struct async_work *async)
{
struct btrfs_multi_bio *multi = NULL;
struct btrfs_device *device;
struct btrfs_root *root = md->root;
u64 bytes_left = async->size;
u64 logical = async->start;
u64 offset = 0;
u64 bytenr;
u64 read_len;
ssize_t done;
int fd;
int num_copies;
int cur_mirror;
int ret;
while (bytes_left) {
read_len = bytes_left;
ret = btrfs_map_block(&md->root->fs_info->mapping_tree, READ,
logical, &read_len, &multi, 0, NULL);
if (ret) {
fprintf(stderr, "Couldn't map data block %d\n", ret);
return ret;
num_copies = btrfs_num_copies(&root->fs_info->mapping_tree, logical,
bytes_left);
/* Try our best to read data, just like read_tree_block() */
for (cur_mirror = 0; cur_mirror < num_copies; cur_mirror++) {
while (bytes_left) {
read_len = bytes_left;
ret = read_extent_data(root,
(char *)(async->buffer + offset),
logical, &read_len, cur_mirror);
if (ret < 0)
break;
offset += read_len;
logical += read_len;
bytes_left -= read_len;
}
device = multi->stripes[0].dev;
if (device->fd <= 0) {
fprintf(stderr,
"Device we need to read from is not open\n");
free(multi);
return -EIO;
}
fd = device->fd;
bytenr = multi->stripes[0].physical;
free(multi);
read_len = min(read_len, bytes_left);
done = pread64(fd, async->buffer+offset, read_len, bytenr);
if (done < read_len) {
if (done < 0)
fprintf(stderr, "Error reading extent %d\n",
errno);
else
fprintf(stderr, "Short read\n");
return -EIO;
}
bytes_left -= done;
offset += done;
logical += done;
}
if (bytes_left)
return -EIO;
return 0;
}