kernel.git/drivers/mtd/ubi/ubi.h, branch linux-6.7.y

ubi: fastmap: Add module parameter to control reserving filling pool PEBs

2023-10-28T21:15:44Z

Adding 6th module parameter in 'mtd=xxx' to control whether or not reserving PEBs for filling pool/wl_pool. Signed-off-by: Zhihao Cheng Signed-off-by: Richard Weinberger

ubi: fastmap: Fix lapsed wear leveling for first 64 PEBs

2023-10-28T21:14:55Z

The anchor PEB must be picked from first 64 PEBs, these PEBs could have large erase counter greater than other PEBs especially when free space is nearly running out. The ubi_update_fastmap will be called as long as pool/wl_pool is empty, old anchor PEB is erased when updating fastmap. Given an UBI device with N PEBs, free PEBs is nearly running out and pool will be filled with 1 PEB every time ubi_update_fastmap invoked. So t=N/POOL_SIZE[1]/64 means that in worst case the erase counter of first 64 PEBs is t times greater than other PEBs in theory. After running fsstress for 24h, the erase counter statistics for two UBI devices shown as follow(CONFIG_MTD_UBI_WL_THRESHOLD=128): Device A(1024 PEBs, pool=50, wl_pool=25): ========================================================= from to count min avg max --------------------------------------------------------- 0 .. 9: 0 0 0 0 10 .. 99: 0 0 0 0 100 .. 999: 0 0 0 0 1000 .. 9999: 0 0 0 0 10000 .. 99999: 960 29224 29282 29362 100000 .. inf: 64 117897 117934 117940 --------------------------------------------------------- Total : 1024 29224 34822 117940 Device B(8192 PEBs, pool=256, wl_pool=128): ========================================================= from to count min avg max --------------------------------------------------------- 0 .. 9: 0 0 0 0 10 .. 99: 0 0 0 0 100 .. 999: 0 0 0 0 1000 .. 9999: 8128 2253 2321 2387 10000 .. 99999: 64 35387 35387 35388 100000 .. inf: 0 0 0 0 --------------------------------------------------------- Total : 8192 2253 2579 35388 The key point is reducing fastmap updating frequency by enlarging POOL_SIZE, so let UBI reserve ubi->fm_pool.max_size PEBs during attaching. Then POOL_SIZE will become ubi->fm_pool.max_size/2 even in free space running out case. Given an UBI device with 8192 PEBs(16384\8192\4096 is common large-capacity flash), t=8192/128/64=1. The fastmap updating will happen in either wl_pool or pool is empty, so setting fm_pool_rsv_cnt as ubi->fm_pool.max_size can fill wl_pool in full state. After pool reservation, running fsstress for 24h: Device A(1024 PEBs, pool=50, wl_pool=25): ========================================================= from to count min avg max --------------------------------------------------------- 0 .. 9: 0 0 0 0 10 .. 99: 0 0 0 0 100 .. 999: 0 0 0 0 1000 .. 9999: 0 0 0 0 10000 .. 99999: 1024 33801 33997 34056 100000 .. inf: 0 0 0 0 --------------------------------------------------------- Total : 1024 33801 33997 34056 Device B(8192 PEBs, pool=256, wl_pool=128): ========================================================= from to count min avg max --------------------------------------------------------- 0 .. 9: 0 0 0 0 10 .. 99: 0 0 0 0 100 .. 999: 0 0 0 0 1000 .. 9999: 8192 2205 2397 2460 10000 .. 99999: 0 0 0 0 100000 .. inf: 0 0 0 0 --------------------------------------------------------- Total : 8192 2205 2397 2460 The difference of erase counter between first 64 PEBs and others is under WL_FREE_MAX_DIFF(2*UBI_WL_THRESHOLD=2*128=256). Device A: 34056 - 33801 = 255 Device B: 2460 - 2205 = 255 Next patch will add a switch to control whether UBI needs to reserve PEBs for filling pool. Fixes: dbb7d2a88d2a ("UBI: Add fastmap core") Link: https://bugzilla.kernel.org/show_bug.cgi?id=217787 Signed-off-by: Zhihao Cheng Signed-off-by: Richard Weinberger

ubi: fastmap: Wait until there are enough free PEBs before filling pools

2023-10-28T20:43:40Z

Wait until there are enough free PEBs before filling pool/wl_pool, sometimes erase_worker is not scheduled in time, which causes two situations: A. There are few PEBs filled in pool, which makes ubi_update_fastmap is frequently called and leads first 64 PEBs are erased more times than other PEBs. So waiting free PEBs before filling pool reduces fastmap updating frequency and prolongs flash service life. B. In situation that space is nearly running out, ubi_refill_pools() cannot make sure pool and wl_pool are filled with free PEBs, caused by the delay of erase_worker. After this patch applied, there must exist free PEBs in pool after one call of ubi_update_fastmap. Besides, this patch is a preparetion for fixing large erase counter in fastmap data block and fixing lapsed wear leveling for first 64 PEBs. Link: https://bugzilla.kernel.org/show_bug.cgi?id=217787 Signed-off-by: Zhihao Cheng Signed-off-by: Richard Weinberger

ubi: Replace erase_block() with sync_erase()

2023-10-28T20:34:24Z

Since erase_block() has same logic with sync_erase(), just replace it with sync_erase(), also rename 'sync_erase()' to 'ubi_sync_erase()'. Signed-off-by: Zhihao Cheng Signed-off-by: Richard Weinberger

ubi: fastmap: Add fastmap control support for 'UBI_IOCATT' ioctl

2022-09-21T16:29:18Z

[1] suggests that fastmap is suitable for large flash devices. Module parameter 'fm_autoconvert' is a coarse grained switch to enable all ubi devices to generate fastmap, which may turn on fastmap even for small flash devices. This patch imports a new field 'disable_fm' in struct 'ubi_attach_req' to support following situations by ioctl 'UBI_IOCATT'. [old functions] A. Disable 'fm_autoconvert': Disbable fastmap for all ubi devices B. Enable 'fm_autoconvert': Enable fastmap for all ubi devices [new function] C. Enable 'fm_autoconvert', set 'disable_fm' for given device: Don't create new fastmap and do full scan (existed fastmap will be destroyed) for the given ubi device. A simple test case in [2]. [1] http://www.linux-mtd.infradead.org/doc/ubi.html#L_fastmap [2] https://bugzilla.kernel.org/show_bug.cgi?id=216278 Signed-off-by: Zhihao Cheng Signed-off-by: Richard Weinberger

ubi: Fix repeated words in comments

2022-09-21T09:32:27Z

Delete the redundant word 'a'. Delete the redundant word 'the'. Signed-off-by: Jilin Yuan Signed-off-by: Richard Weinberger

ubi: fastmap: Fix high cpu usage of ubi_bgt by making sure wl_pool not empty

2022-05-27T14:46:02Z

There at least 6 PEBs reserved on UBI device: 1. EBA_RESERVED_PEBS[1] 2. WL_RESERVED_PEBS[1] 3. UBI_LAYOUT_VOLUME_EBS[2] 4. MIN_FASTMAP_RESERVED_PEBS[2] When all ubi volumes take all their PEBs, there are 3 (EBA_RESERVED_PEBS + WL_RESERVED_PEBS + MIN_FASTMAP_RESERVED_PEBS - MIN_FASTMAP_TAKEN_PEBS[1]) free PEBs. Since commit f9c34bb529975fe ("ubi: Fix producing anchor PEBs") and commit 4b68bf9a69d22dd ("ubi: Select fastmap anchor PEBs considering wear level rules") applied, there is only 1 (3 - FASTMAP_ANCHOR_PEBS[1] - FASTMAP_NEXT_ANCHOR_PEBS[1]) free PEB to fill pool and wl_pool, after filling pool, wl_pool is always empty. So, UBI could be stuck in an infinite loop: ubi_thread system_wq wear_leveling_worker <-------------------------------------------------- get_peb_for_wl | // fm_wl_pool, used = size = 0 | schedule_work(&ubi->fm_work) | | update_fastmap_work_fn | ubi_update_fastmap | ubi_refill_pools | // ubi->free_count - ubi->beb_rsvd_pebs < 5 | // wl_pool is not filled with any PEBs | schedule_erase(old_fm_anchor) | ubi_ensure_anchor_pebs | __schedule_ubi_work(wear_leveling_worker) | | __erase_worker | ensure_wear_leveling | __schedule_ubi_work(wear_leveling_worker) -------------------------- , which cause high cpu usage of ubi_bgt: top - 12:10:42 up 5 min, 2 users, load average: 1.76, 0.68, 0.27 Tasks: 123 total, 3 running, 54 sleeping, 0 stopped, 0 zombie PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 1589 root 20 0 0 0 0 R 45.0 0.0 0:38.86 ubi_bgt0d 319 root 20 0 0 0 0 I 15.2 0.0 0:15.29 kworker/0:3-eve 371 root 20 0 0 0 0 I 14.9 0.0 0:12.85 kworker/3:3-eve 20 root 20 0 0 0 0 I 11.3 0.0 0:05.33 kworker/1:0-eve 202 root 20 0 0 0 0 I 11.3 0.0 0:04.93 kworker/2:3-eve In commit 4b68bf9a69d22dd ("ubi: Select fastmap anchor PEBs considering wear level rules"), there are three key changes: 1) Choose the fastmap anchor when the most free PEBs are available. 2) Enable anchor move within the anchor area again as it is useful for distributing wear. 3) Import a candidate fm anchor and check this PEB's erase count during wear leveling. If the wear leveling limit is exceeded, use the used anchor area PEB with the lowest erase count to replace it. The anchor candidate can be removed, we can check fm_anchor PEB's erase count during wear leveling. Fix it by: 1) Removing 'fm_next_anchor' and check 'fm_anchor' during wear leveling. 2) Preferentially filling one free peb into fm_wl_pool in condition of ubi->free_count > ubi->beb_rsvd_pebs, then try to reserve enough free count for fastmap non anchor pebs after the above prerequisites are met. Then, there are at least 1 PEB in pool and 1 PEB in wl_pool after calling ubi_refill_pools() with all erase works done. Fetch a reproducer in [Link]. Fixes: 4b68bf9a69d22dd ("ubi: Select fastmap anchor PEBs ... rules") Link: https://bugzilla.kernel.org/show_bug.cgi?id=215407 Signed-off-by: Zhihao Cheng Signed-off-by: Richard Weinberger

ubi: Remove unnecessary struct declaration

2021-04-15T20:01:25Z

struct ubi_wl_entry is defined at 178th line. The declaration here is unnecessary. Remove it. Reviewed-by: Tudor Ambarus Signed-off-by: Wan Jiabing Signed-off-by: Richard Weinberger

Merge tag 'for-linus-5.8-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rw/ubifs

2020-06-10T20:24:40Z

Pull UBI update from Richard Weinberger: "This contains a single change for UBI: - Select fastmap anchor PEBs considering wear level rules" * tag 'for-linus-5.8-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rw/ubifs: ubi: Select fastmap anchor PEBs considering wear level rules

mm: introduce include/linux/pgtable.h

2020-06-09T16:39:13Z

The include/linux/pgtable.h is going to be the home of generic page table manipulation functions. Start with moving asm-generic/pgtable.h to include/linux/pgtable.h and make the latter include asm/pgtable.h. Signed-off-by: Mike Rapoport Signed-off-by: Andrew Morton Cc: Arnd Bergmann Cc: Borislav Petkov Cc: Brian Cain Cc: Catalin Marinas Cc: Chris Zankel Cc: "David S. Miller" Cc: Geert Uytterhoeven Cc: Greentime Hu Cc: Greg Ungerer Cc: Guan Xuetao Cc: Guo Ren Cc: Heiko Carstens Cc: Helge Deller Cc: Ingo Molnar Cc: Ley Foon Tan Cc: Mark Salter Cc: Matthew Wilcox Cc: Matt Turner Cc: Max Filippov Cc: Michael Ellerman Cc: Michal Simek Cc: Nick Hu Cc: Paul Walmsley Cc: Richard Weinberger Cc: Rich Felker Cc: Russell King Cc: Stafford Horne Cc: Thomas Bogendoerfer Cc: Thomas Gleixner Cc: Tony Luck Cc: Vincent Chen Cc: Vineet Gupta Cc: Will Deacon Cc: Yoshinori Sato Link: http://lkml.kernel.org/r/20200514170327.31389-3-rppt@kernel.org Signed-off-by: Linus Torvalds