Most recent kernel where this bug did not occur: N/A Distribution: this bug does not depend on distribution. Hardware Environment: x86 Software Environment: >>> # lsmod Module Size Used by bfs 14008 1 # <<< Problem Description: When creating new files or extending existing files, the BFS filesystem driver does not take into account the size of the underlying block device. As a result, if a big enough file is created on a BFS partition, the bio layer reports the "attempt to access beyond end of device" error. Besides, the filesystem statistical information gets corrupted. Steps to reproduce: 1. Mount an empty BFS partition. In the example below, the filesystem resides on the loopback device `/dev/loop0' and is mounted to `/mnt'. 2. Try to create a big file on this partition. This file needs to be bigger than the amount of free space on the BFS partition. Here we create a file, which is one block bigger than the number of free blocks available on the BFS partition: >>> root@codedot:/mnt# mount | grep mnt /dev/loop0 on /mnt type bfs (rw) root@codedot:/mnt# df -B 512 | grep loop /dev/loop0 65536 81 65455 1% /mnt root@codedot:/mnt# dd if=/dev/zero of=/mnt/1 bs=512 count=65456 65456+0 records in 65456+0 records out 33513472 bytes (34 MB) copied, 2.81289 seconds, 11.9 MB/s root@codedot:/mnt# df -B 512 | grep loop /dev/loop0 65536 -4294901759 4294967295 - /mnt <<< 3. Look at the kernel log and see the attempts to write beyond the end of the loop0 block device: >>> root@codedot:/mnt# dmesg | tail [ 9099.861883] attempt to access beyond end of device [ 9099.862029] loop0: rw=1, want=65537, limit=65536 [ 9099.862119] Buffer I/O error on device loop0, logical block 65536 [ 9099.862199] lost page write due to I/O error on loop0 root@codedot:/mnt# <<<
The bfs_get_block() function located in `fs/bfs/file.c' does not compare the number of the physical block, which it tries to access when extending the file, against the size of the block device. Checks against the block device size need to be introduced into the filesystem driver, and -ENOSPC error should be returned every time the partition runs out of free space when writing a growing file. The patch, which fixes this problem will soon be submitted, I am working on that.
The patch proposed in the following LKML message http://lkml.org/lkml/2007/11/13/185 fixes the error reported in the context of this bug. What follows is a console session, which proves that the error is gone: >>> debian:~# mount -t bfs /dev/loop0 /mnt debian:~# cd /mnt debian:/mnt# mount | grep mnt /dev/loop0 on /mnt type bfs (rw) debian:/mnt# df -B 512 | grep loop /dev/loop0 65536 81 65455 1% /mnt debian:/mnt# dd if=/dev/zero of=/mnt/1 bs=512 count=65456 dd: writing `/mnt/1': No space left on device 65456+0 records in 65455+0 records out 33512960 bytes (34 MB) copied, 7.07956 seconds, 4.7 MB/s debian:/mnt# df -B 512 | grep loop /dev/loop0 65536 65536 0 100% /mnt debian:/mnt# <<<
I merged Dmitri's fix.