kernel/linux.git/drivers/mtd/mtdblock.c, branch v5.18.2

mtdblock: Warn if added for a NAND device

2021-08-17T16:41:59+00:00

There is a surprisingly large number of tutorials that suggest using mtdblock to mount SquashFS filesystems on flash devices, including NAND devices. This approach is suboptimal than using UBI. If the flash device is NAND, this is specially true, due to wear leveling, bit-flips and badblocks. In this case UBI is strongly preferred, so be nice to users and print a warning suggesting to consider UBI block, if mtdblock is added for a NAND device. Signed-off-by: Ezequiel Garcia Signed-off-by: Miquel Raynal Link: https://lore.kernel.org/linux-mtd/20210801234509.18774-8-ezequiel@collabora.com

mtd: mtdblock: Use module_mtd_blktrans to register driver

2021-03-11T08:37:48+00:00

Removing some boilerplate by using module_mtd_blktrans instead of calling register and unregister in the otherwise empty init/exit functions. Signed-off-by: Dejin Zheng Signed-off-by: Miquel Raynal Link: https://lore.kernel.org/linux-mtd/20210213164600.409061-5-zhengdejin5@gmail.com

mtd: clear cache_state to avoid writing to bad blocks repeatedly

2020-06-05T08:16:14+00:00

The function call process is as follows: mtd_blktrans_work() while (1) do_blktrans_request() mtdblock_writesect() do_cached_write() write_cached_data() /*if cache_state is STATE_DIRTY*/ erase_write() write_cached_data() returns failure without modifying cache_state and cache_offset. So when do_cached_write() is called again, write_cached_data() will be called again to perform erase_write() on the same cache_offset. But if this cache_offset points to a bad block, erase_write() will always return -EIO. Writing to this mtdblk is equivalent to losing the current data, and repeatedly writing to the bad block. Repeatedly writing a bad block has no real benefits, but brings some negative effects: 1 Lost subsequent data 2 Loss of flash device life 3 erase_write() bad blocks are very time-consuming. For example: the function do_erase_oneblock() in chips/cfi_cmdset_0020.c or chips/cfi_cmdset_0002.c may take more than 20 seconds to return Therefore, when erase_write() returns -EIO in write_cached_data(), clear cache_state to avoid writing to bad blocks repeatedly. Signed-off-by: Xiaoming Ni Reviewed-by: Miquel Raynal Signed-off-by: Richard Weinberger

mtd: Fix issue where write_cached_data() fails but write() still returns success

2020-03-24T22:02:30+00:00

The following sequence is problematic: mtdblock_flush() -->write_cached_data() --->erase_write() mtdblock: erase of region [0x40000, 0x20000] on "xxx" failed Problem is: mtdblock_flush() always returns 0. Indeed, even if write_cached_data() fails and data is not written to the device, syscall_write() still returns success. Avoid this situation by actually returning the error coming out of write_cached_data(). Signed-off-by: Xiaoming Ni Signed-off-by: Miquel Raynal Link: https://lore.kernel.org/linux-mtd/1584674111-101462-1-git-send-email-nixiaoming@huawei.com

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 102

2019-05-24T15:39:00+00:00

Based on 1 normalized pattern(s): this program is free software you can redistribute it and or modify it under the terms of the gnu general public license as published by the free software foundation either version 2 of the license or at your option any later version this program is distributed in the hope that it will be useful but without any warranty without even the implied warranty of merchantability or fitness for a particular purpose see the gnu general public license for more details you should have received a copy of the gnu general public license along with this program if not write to the free software foundation inc 51 franklin st fifth floor boston ma 02110 1301 usa extracted by the scancode license scanner the SPDX license identifier GPL-2.0-or-later has been chosen to replace the boilerplate/reference in 50 file(s). Signed-off-by: Thomas Gleixner Reviewed-by: Kate Stewart Reviewed-by: Allison Randal Reviewed-by: Richard Fontana Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190523091649.499889647@linutronix.de Signed-off-by: Greg Kroah-Hartman

mtd: change len type from signed to unsigned type

2018-12-03T10:32:26+00:00

Callers of erase_write() always pass an unsigned int. So this patch avoids a cast to an int. Signed-off-by: huijin.park Reviewed-by: Miquel Raynal Signed-off-by: Boris Brezillon

mtd: Unconditionally update ->fail_addr and ->addr in part_erase()

2018-03-15T17:22:26+00:00

->fail_addr and ->addr can be updated no matter the result of parent->_erase(), we just need to remove the code doing the same thing in mtd_erase_callback() to avoid adjusting those fields twice. Note that this can be done because all MTD users have been converted to not pass an erase_info->callback() and are thus only taking the ->addr_fail and ->addr fields into account after part_erase() has returned. While we're at it, get rid of the erase_info->mtd field which was only needed to let mtd_erase_callback() get the partition device back. Signed-off-by: Boris Brezillon Reviewed-by: Richard Weinberger

mtd: Stop assuming mtd_erase() is asynchronous

2018-03-15T17:21:07+00:00

None of the mtd->_erase() implementations work in an asynchronous manner, so let's simplify MTD users that call mtd_erase(). All they need to do is check the value returned by mtd_erase() and assume that != 0 means failure. Signed-off-by: Boris Brezillon Reviewed-by: Richard Weinberger

mtd: mtdblock: remove the needless mtdblks_lock

2015-01-07T20:51:56+00:00

The global lock mtdblks_lock was used to protect the original mtdblks array to avoid race conditions. As the mtdblks array was already gone, but the mtdblks_lock is left, and it causes latency when open/release dev. So we need to remove it here. Signed-off-by: Gu Zheng Signed-off-by: Brian Norris

mtd: Move major number definitions to major.h

2013-11-07T07:32:59+00:00

This patch moves the char and block major number definitions to major.h to be with the rest of the major numbers. While doing this, include major.h in the files that need it. Signed-off-by: Ezequiel Garcia Signed-off-by: Brian Norris