kernel.git/drivers/mtd/ubi/ubi.h, branch linux-4.6.y

UBI: Fix static volume checks when Fastmap is used

2016-06-01T19:18:05Z

commit 1900149c835ab5b48bea31a823ea5e5a401fb560 upstream. Ezequiel reported that he's facing UBI going into read-only mode after power cut. It turned out that this behavior happens only when updating a static volume is interrupted and Fastmap is used. A possible trace can look like: ubi0 warning: ubi_io_read_vid_hdr [ubi]: no VID header found at PEB 2323, only 0xFF bytes ubi0 warning: ubi_eba_read_leb [ubi]: switch to read-only mode CPU: 0 PID: 833 Comm: ubiupdatevol Not tainted 4.6.0-rc2-ARCH #4 Hardware name: SAMSUNG ELECTRONICS CO., LTD. 300E4C/300E5C/300E7C/NP300E5C-AD8AR, BIOS P04RAP 10/15/2012 0000000000000286 00000000eba949bd ffff8800c45a7b38 ffffffff8140d841 ffff8801964be000 ffff88018eaa4800 ffff8800c45a7bb8 ffffffffa003abf6 ffffffff850e2ac0 8000000000000163 ffff8801850e2ac0 ffff8801850e2ac0 Call Trace: [] dump_stack+0x63/0x82 [] ubi_eba_read_leb+0x486/0x4a0 [ubi] [] ubi_check_volume+0x83/0xf0 [ubi] [] ubi_open_volume+0x177/0x350 [ubi] [] vol_cdev_open+0x58/0xb0 [ubi] [] chrdev_open+0xae/0x1d0 [] do_dentry_open+0x1ff/0x300 [] ? cdev_put+0x30/0x30 [] vfs_open+0x56/0x60 [] path_openat+0x4f4/0x1190 [] do_filp_open+0x91/0x100 [] ? __alloc_fd+0xc7/0x190 [] do_sys_open+0x13f/0x210 [] SyS_open+0x1e/0x20 [] entry_SYSCALL_64_fastpath+0x1a/0xa4 UBI checks static volumes for data consistency and reads the whole volume upon first open. If the volume is found erroneous users of UBI cannot read from it, but another volume update is possible to fix it. The check is performed by running ubi_eba_read_leb() on every allocated LEB of the volume. For static volumes ubi_eba_read_leb() computes the checksum of all data stored in a LEB. To verify the computed checksum it has to read the LEB's volume header which stores the original checksum. If the volume header is not found UBI treats this as fatal internal error and switches to RO mode. If the UBI device was attached via a full scan the assumption is correct, the volume header has to be present as it had to be there while scanning to get known as mapped. If the attach operation happened via Fastmap the assumption is no longer correct. When attaching via Fastmap UBI learns the mapping table from Fastmap's snapshot of the system state and not via a full scan. It can happen that a LEB got unmapped after a Fastmap was written to the flash. Then UBI can learn the LEB still as mapped and accessing it returns only 0xFF bytes. As UBI is not a FTL it is allowed to have mappings to empty PEBs, it assumes that the layer above takes care of LEB accounting and referencing. UBIFS does so using the LEB property tree (LPT). For static volumes UBI blindly assumes that all LEBs are present and therefore special actions have to be taken. The described situation can happen when updating a static volume is interrupted, either by a user or a power cut. The volume update code first unmaps all LEBs of a volume and then writes LEB by LEB. If the sequence of operations is interrupted UBI detects this either by the absence of LEBs, no volume header present at scan time, or corrupted payload, detected via checksum. In the Fastmap case the former method won't trigger as no scan happened and UBI automatically thinks all LEBs are present. Only by reading data from a LEB it detects that the volume header is missing and incorrectly treats this as fatal error. To deal with the situation ubi_eba_read_leb() from now on checks whether we attached via Fastmap and handles the absence of a volume header like a data corruption error. This way interrupted static volume updates will correctly get detected also when Fastmap is used. Reported-by: Ezequiel Garcia Tested-by: Ezequiel Garcia Signed-off-by: Richard Weinberger Signed-off-by: Greg Kroah-Hartman

mtd: ubi: Add logging functions ubi_msg, ubi_warn and ubi_err

2016-03-20T20:36:05Z

Using logging functions instead of macros can reduce overall object size. $ size drivers/mtd/ubi/built-in.o* text data bss dec hex filename 271620 163364 73696 508680 7c308 drivers/mtd/ubi/built-in.o.allyesconfig.new 287638 165380 73504 526522 808ba drivers/mtd/ubi/built-in.o.allyesconfig.old 87728 3780 504 92012 1676c drivers/mtd/ubi/built-in.o.defconfig.new 97084 3780 504 101368 18bf8 drivers/mtd/ubi/built-in.o.defconfig.old Signed-off-by: Joe Perches Signed-off-by: Richard Weinberger

UBI: Use static class and attribute groups

2015-06-02T11:16:25Z

This patch cleans up the manual device_create_file() or class_create_file() calls by replacing with static attribute groups. It simplifies the code and also avoids the possible races between the device/class registration and sysfs creations. For the simplification, also make ubi_class a static instance with initializers, too. Amend a bit by Hujianyang. Signed-off-by: Takashi Iwai Tested-by: Sheng Yong Signed-off-by: hujianyang Signed-off-by: Richard Weinberger

UBI: power cut emulation for testing

2015-04-13T19:05:17Z

Emulate random power cuts by switching device to ro after a number of writes to allow simple power cut testing with nand-sim. Maximum and minimum number of successful writes before power cut and what kind of writes (EC header, VID header or none) to interrupt configurable via debugfs. Signed-off-by: David Oberhollenzer Signed-off-by: Richard Weinberger

UBI: Add accessor functions for WL data structures

2015-03-26T21:47:35Z

Fastmap need access to various WL data structures as fastmap tightly depends on WL. To make the access less invasive add accessor functions. Signed-off-by: Richard Weinberger

UBI: Add initial support for fastmap self checks

2015-03-26T21:46:03Z

Using this debugfs knob fastmap self checks can be controlled. Signed-off-by: Richard Weinberger Reviewed-by: Tanya Brokhman

UBI: Fastmap: Locking updates

2015-03-26T21:46:02Z

a) Rename ubi->fm_sem to ubi->fm_eba_sem as this semaphore protects EBA changes. b) Turn ubi->fm_mutex into a rw semaphore. It will still serialize fastmap writes but also ensures that ubi_wl_put_peb() is not interrupted by a fastmap write. We use a rw semaphore to allow ubi_wl_put_peb() still to be executed in parallel if no fastmap write is happening. Signed-off-by: Richard Weinberger

UBI: Fastmap: Wrap fastmap specific function in a ifdef

2015-03-26T21:45:56Z

...such that we can implement NOP variants of some functions. This will help to reduce fastmap specific ifdefs in other c files. Signed-off-by: Richard Weinberger Reviewed-by: Tanya Brokhman

UBI: Fastmap: Fix races in ubi_wl_get_peb()

2015-03-26T20:24:24Z

ubi_wl_get_peb() has two problems, it reads the pool size and usage counters without any protection. While reading one value would be perfectly fine it reads multiple values and compares them. This is racy and can lead to incorrect pool handling. Furthermore ubi_update_fastmap() is called without wl_lock held, before incrementing the used counter it needs to be checked again. It could happen that another thread consumed all PEBs from the pool and the counter goes beyond ->size. Signed-off-by: Richard Weinberger

UBI: Fastmap: Ensure that only one fastmap work is scheduled

2015-03-26T18:30:54Z

If the WL pool runs out of PEBs we schedule a fastmap write to refill it as soon as possible. Ensure that only one at a time is scheduled otherwise we might end in a fastmap write storm because writing the fastmap can schedule another write if bitflips are detected. Signed-off-by: Richard Weinberger Reviewed-by: Tanya Brokhman Reviewed-by: Guido Martínez