Hello,
Hello, I have hit the following situation when trying to load files from a
BTRFS partition with duplication enabled.
In the first example I read a 16KiB file - __btrfs_map_block() changes the
length to something larger than the file being read. This works fine, as length
is later clamped to the file size.
In the second example, __btrfs_map_block() changes the length parameter to
something smaller than the file (the size of a stripe). This seems to break
this check here:
read = len;
num_copies = btrfs_num_copies(fs_info, logical, len);
for (i = 1; i <= num_copies; i++) {
ret = read_extent_data(fs_info, dest, logical, &read, i);
if (ret < 0 || read != len) {
continue;
}
finished = true;
break;
}
The problem being that read is always less than len.
I am not sure if __btrfs_map_block is changing "len" to the incorrect value, or
if there is some logic in "read_extent_data" that isn't correct. Any pointers
on how this code is supposed to work would be greatly appreciated.
Thanks.
=== EXAMPLE 2 ===
Zynq> load mmc 1:0 0 16K
[btrfs_file_read,fs/btrfs/inode.c:710] === read the aligned part ===
[btrfs_read_extent_reg,fs/btrfs/inode.c:458] before read_extent_data (ret = 0,
read = 16384, len = 16384)
[read_extent_data,fs/btrfs/disk-io.c:547] before __btrfs_map_block (len = 16384)
[read_extent_data,fs/btrfs/disk-io.c:550] after __btrfs_map_block (len = 28672)
[read_extent_data,fs/btrfs/disk-io.c:565] before __btrfs_devread (len = 16384)
[read_extent_data,fs/btrfs/disk-io.c:568] after __btrfs_devread (len = 16384)
[btrfs_read_extent_reg,fs/btrfs/inode.c:460] after read_extent_data (ret = 0,
read = 16384, len = 16384)
cur: 0, extent_num_bytes: 16384, aligned_end: 16384
16384 bytes read in 100 ms (159.2 KiB/s)
=== EXAMPLE 2 ===
Zynq> load mmc 1:0 0 32K
[btrfs_file_read,fs/btrfs/inode.c:710] === read the aligned part ===
[btrfs_read_extent_reg,fs/btrfs/inode.c:458] before read_extent_data (ret = 0,
read = 32768, len = 32768)
[read_extent_data,fs/btrfs/disk-io.c:547] before __btrfs_map_block (len = 32768)
[read_extent_data,fs/btrfs/disk-io.c:550] after __btrfs_map_block (len = 12288)
[read_extent_data,fs/btrfs/disk-io.c:565] before __btrfs_devread (len = 12288)
[read_extent_data,fs/btrfs/disk-io.c:568] after __btrfs_devread (len = 12288)
[btrfs_read_extent_reg,fs/btrfs/inode.c:460] after read_extent_data (ret = 0,
read = 12288, len = 32768)
[btrfs_read_extent_reg,fs/btrfs/inode.c:458] before read_extent_data (ret = 0,
read = 12288, len = 32768)
[read_extent_data,fs/btrfs/disk-io.c:547] before __btrfs_map_block (len = 12288)
[read_extent_data,fs/btrfs/disk-io.c:550] after __btrfs_map_block (len = 12288)
[read_extent_data,fs/btrfs/disk-io.c:565] before __btrfs_devread (len = 12288)
[read_extent_data,fs/btrfs/disk-io.c:568] after __btrfs_devread (len = 12288)
[btrfs_read_extent_reg,fs/btrfs/inode.c:460] after read_extent_data (ret = 0,
read = 12288, len = 32768)
file: fs/btrfs/inode.c, line: 468
cur: 0, extent_num_bytes: 32768, aligned_end: 32768
-----> btrfs_read_extent_reg: -5, line: 758
BTRFS: An error occurred while reading file 32K
Failed to load '32K'
Sam Winchenbach
Embedded Software Engineer III
Tethers Unlimited, Inc. | Connect Your Universe | www.tethers.com
swinchenb...@tethers.com | C: 207-974-6934
11711 North Creek Pkwy # D113, Bothell, WA 98011-8808, USA
CONFIDENTIALITY NOTE: The information contained in this transmission may be
privileged and confidential information and is intended only for the use of the
individual or entity named above. If the reader of this message is not the
intended recipient, you are hereby notified that any dissemination,
distribution or copying of this communication is strictly prohibited. If you
have received this transmission in error, please immediately reply to the
sender that you have received this communication in error and then delete it.
Thank you.
ITAR/EAR NOTICE: This email and/or attachments may contain technical data
controlled by the US International Traffic and Arms Regulations (ITAR) or the
Export Administration Regulations (EAR). Export from the US or disclosure to
foreign nationals in the U.S. without an export license is a violation of law.
It is the recipient's responsibility to assure this item can be legally shared
with another party.
