Messages in this thread Patch in this message | | | Date | Thu, 25 Jul 2002 15:26:19 +0200 (MET DST) | From | Mikael Pettersson <> | Subject | [PATCH][2.5.28] broken floppy driver workarounds, take 4 |
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Here's the 4th version of my patch to "fix" the floppy driver which got broken by the 2.5.13-2.5.19 and 2.5.28 block dev changes.
In 2.5.28 there was a change in fs/block_dev.c which set the floppy block dev's size to 0, and this causes ENOSPC errors on writes to the floppy dev. This 4th version of the patch adds a workaround for this problem.
Partial VFS access _may_ work now. I created an ext2 fs on /dev/fd0 under 2.5.28+this patch, and it fsck'd ok under both 2.5.28 and 2.4.19rc3. However, when I attempted to put lilo on that floppy the kernel oopsed with a "buffer layer error at buffer.c:403", so things are still not quite right.
/Mikael
diff -ruN linux-2.5.28/drivers/block/floppy.c linux-2.5.28.fix-floppy/drivers/block/floppy.c --- linux-2.5.28/drivers/block/floppy.c Thu Jul 25 01:27:30 2002 +++ linux-2.5.28.fix-floppy/drivers/block/floppy.c Thu Jul 25 14:33:49 2002 @@ -3699,6 +3699,10 @@ UDRS->fd_ref = 0; } floppy_release_irq_and_dma(); + + /* undo ++bd_openers in floppy_open() */ + --inode->i_bdev->bd_openers; + return 0; } @@ -3791,6 +3795,43 @@ invalidate_buffers(mk_kdev(FLOPPY_MAJOR,old_dev)); } + /* Problems: + * 1. floppy_open() triggers a call to submit_bio(), but + * bdev->bd_queue may be NULL since it is not set up until + * after floppy_open() has returned. Prior to 2.5.18, NULL + * queues were initialised when needed. + * 2. fs/block_dev.c:do_open() changes bdev's block size + * after floppy_open() has returned. For some reason, this + * causes data corruption durings writes. + * 3. fs/block_dev.c:do_open() sets bdev->bd_inode->i_size to 0 + * after floppy_open() has returned. This cases ENOSPC errors + * on writes. + * Workarounds: + * 1. bdev->bd_queue is initialised here. + * 2. Set bdev block size equal to the hardsect/queue size. + * This seems to cure the data corruption problem for raw + * accesses. VFS accesses to mounted floppies still cause + * data corruption for unknown reasons. + * 3. Set i_size to 1.44M and bd_offset to 0. + * 2&3. ++bdev->bd_openers to bypass do_open()'s changes. + * floppy_release() does a --bdev->bd_openers. + */ + { + struct block_device *bdev = inode->i_bdev; + kdev_t dev = inode->i_rdev; + struct blk_dev_struct *p = blk_dev + major(dev); + + if (p->queue) + bdev->bd_queue = p->queue(dev); + else + bdev->bd_queue = &p->request_queue; + bdev->bd_block_size = bdev_hardsect_size(bdev); + bdev->bd_inode->i_blkbits = blksize_bits(block_size(bdev)); + bdev->bd_offset = 0; + bdev->bd_inode->i_size = 1440 * 1024; + ++bdev->bd_openers; + } + /* Allow ioctls if we have write-permissions even if read-only open. * Needed so that programs such as fdrawcmd still can work on write * protected disks */ @@ -4228,8 +4269,6 @@ { int i,unit,drive; - register_sys_device(&device_floppy); - raw_cmd = NULL; devfs_handle = devfs_mk_dir (NULL, "floppy", NULL); @@ -4356,6 +4395,9 @@ register_disk(NULL, mk_kdev(MAJOR_NR,TOMINOR(drive)+i*4), 1, &floppy_fops, 0); } + + register_sys_device(&device_floppy); + return have_no_fdc; } @@ -4538,6 +4580,7 @@ { int dummy; + unregister_sys_device(&device_floppy); devfs_unregister (devfs_handle); devfs_unregister_blkdev(MAJOR_NR, "fd"); - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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