1. 27 Nov, 2017 1 commit
    • Linus Torvalds's avatar
      Rename superblock flags (MS_xyz -> SB_xyz) · 1751e8a6
      Linus Torvalds authored
      This is a pure automated search-and-replace of the internal kernel
      superblock flags.
      The s_flags are now called SB_*, with the names and the values for the
      moment mirroring the MS_* flags that they're equivalent to.
      Note how the MS_xyz flags are the ones passed to the mount system call,
      while the SB_xyz flags are what we then use in sb->s_flags.
      The script to do this was:
          # places to look in; re security/*: it generally should *not* be
          # touched (that stuff parses mount(2) arguments directly), but
          # there are two places where we really deal with superblock flags.
          FILES="drivers/mtd drivers/staging/lustre fs ipc mm \
                  include/linux/fs.h include/uapi/linux/bfs_fs.h \
                  security/apparmor/apparmorfs.c security/apparmor/include/lib.h"
          # the list of MS_... constants
                ACTIVE NOUSER"
          for i in $SYMS; do SED_PROG="$SED_PROG -e s/MS_$i/SB_$i/g"; done
          # we want files that contain at least one of MS_...,
          # with fs/namespace.c and fs/pnode.c excluded.
          L=$(for i in $SYMS; do git grep -w -l MS_$i $FILES; done| sort|uniq|grep -v '^fs/namespace.c'|grep -v '^fs/pnode.c')
          for f in $L; do sed -i $f $SED_PROG; done
      Requested-by: 's avatarAl Viro <viro@zeniv.linux.org.uk>
      Signed-off-by: 's avatarLinus Torvalds <torvalds@linux-foundation.org>
  2. 10 Oct, 2017 1 commit
  3. 04 Oct, 2017 1 commit
    • Jens Axboe's avatar
      writeback: eliminate work item allocation in bd_start_writeback() · 85009b4f
      Jens Axboe authored
      Handle start-all writeback like we do periodic or kupdate
      style writeback - by marking the bdi_writeback as needing a full
      flush, and simply waking the thread. This eliminates the need to
      allocate and queue a specific work item just for this purpose.
      After this change, we truly only ever have one of them running at
      any point in time. We mark the need to start all flushes, and the
      writeback thread will clear it once it has processed the request.
      Reviewed-by: 's avatarJan Kara <jack@suse.cz>
      Signed-off-by: 's avatarJens Axboe <axboe@kernel.dk>
  4. 03 Oct, 2017 7 commits
  5. 12 Jul, 2017 1 commit
  6. 16 May, 2017 1 commit
  7. 13 Mar, 2017 1 commit
  8. 13 Dec, 2016 1 commit
  9. 10 Aug, 2016 1 commit
    • Konstantin Khlebnikov's avatar
      mm, writeback: flush plugged IO in wakeup_flusher_threads() · 51350ea0
      Konstantin Khlebnikov authored
      I've found funny live-lock between raid10 barriers during resync and
      memory controller hard limits. Inside mpage_readpages() task holds on to
      its plug bio which blocks the barrier in raid10. Its memory cgroup have
      no free memory thus the task goes into reclaimer but all reclaimable
      pages are dirty and cannot be written because raid10 is rebuilding and
      stuck on the barrier.
      Common flush of such IO in schedule() never happens, because the caller
      doesn't go to sleep.
      Lock is 'live' because changing memory limit or killing tasks which
      holds that stuck bio unblock whole progress.
      That was what happened in 3.18.x but I see no difference in upstream
      logic.  Theoretically this might happen even without memory cgroup.
      Signed-off-by: 's avatarKonstantin Khlebnikov <khlebnikov@yandex-team.ru>
      Signed-off-by: 's avatarJens Axboe <axboe@fb.com>
  10. 04 Aug, 2016 1 commit
    • Jan Kara's avatar
      writeback: Write dirty times for WB_SYNC_ALL writeback · dc5ff2b1
      Jan Kara authored
      Currently we take care to handle I_DIRTY_TIME in vfs_fsync() and
      queue_io() so that inodes which have only dirty timestamps are properly
      written on fsync(2) and sync(2). However there are other call sites -
      most notably going through write_inode_now() - which expect inode to be
      clean after WB_SYNC_ALL writeback. This is not currently true as we do
      not clear I_DIRTY_TIME in __writeback_single_inode() even for
      WB_SYNC_ALL writeback in all the cases. This then resulted in the
      following oops because bdev_write_inode() did not clean the inode and
      writeback code later stumbled over a dirty inode with detached wb.
        general protection fault: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN
        Modules linked in:
        CPU: 3 PID: 32 Comm: kworker/u10:1 Not tainted 4.6.0-rc3+ #349
        Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
        Workqueue: writeback wb_workfn (flush-11:0)
        task: ffff88006ccf1840 ti: ffff88006cda8000 task.ti: ffff88006cda8000
        RIP: 0010:[<ffffffff818884d2>]  [<ffffffff818884d2>]
        RSP: 0018:ffff88006cdaf7d0  EFLAGS: 00010246
        RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffff88006ccf2050
        RDX: 0000000000000000 RSI: 000000114c8a8484 RDI: 0000000000000286
        RBP: ffff88006cdaf820 R08: ffff88006ccf1840 R09: 0000000000000000
        R10: 000229915090805f R11: 0000000000000001 R12: ffff88006a72f5e0
        R13: dffffc0000000000 R14: ffffed000d4e5eed R15: ffffffff8830cf40
        FS:  0000000000000000(0000) GS:ffff88006d500000(0000) knlGS:0000000000000000
        CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
        CR2: 0000000003301bf8 CR3: 000000006368f000 CR4: 00000000000006e0
        DR0: 0000000000001ec9 DR1: 0000000000000000 DR2: 0000000000000000
        DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
         ffff88006a72f680 ffff88006a72f768 ffff8800671230d8 03ff88006cdaf948
         ffff88006a72f668 ffff88006a72f5e0 ffff8800671230d8 ffff88006cdaf948
         ffff880065b90cc8 ffff880067123100 ffff88006cdaf970 ffffffff8188e12e
        Call Trace:
         [<     inline     >] inode_to_wb_and_lock_list fs/fs-writeback.c:309
         [<ffffffff8188e12e>] writeback_sb_inodes+0x4de/0x1250 fs/fs-writeback.c:1554
         [<ffffffff8188efa4>] __writeback_inodes_wb+0x104/0x1e0 fs/fs-writeback.c:1600
         [<ffffffff8188f9ae>] wb_writeback+0x7ce/0xc90 fs/fs-writeback.c:1709
         [<     inline     >] wb_do_writeback fs/fs-writeback.c:1844
         [<ffffffff81891079>] wb_workfn+0x2f9/0x1000 fs/fs-writeback.c:1884
         [<ffffffff813bcd1e>] process_one_work+0x78e/0x15c0 kernel/workqueue.c:2094
         [<ffffffff813bdc2b>] worker_thread+0xdb/0xfc0 kernel/workqueue.c:2228
         [<ffffffff813cdeef>] kthread+0x23f/0x2d0 drivers/block/aoe/aoecmd.c:1303
         [<ffffffff867bc5d2>] ret_from_fork+0x22/0x50 arch/x86/entry/entry_64.S:392
        Code: 05 94 4a a8 06 85 c0 0f 85 03 03 00 00 e8 07 15 d0 ff 41 80 3e
        00 0f 85 64 06 00 00 49 8b 9c 24 88 01 00 00 48 89 d8 48 c1 e8 03 <42>
        80 3c 28 00 0f 85 17 06 00 00 48 8b 03 48 83 c0 50 48 39 c3
        RIP  [<     inline     >] wb_get include/linux/backing-dev-defs.h:212
        RIP  [<ffffffff818884d2>] locked_inode_to_wb_and_lock_list+0xa2/0x750
         RSP <ffff88006cdaf7d0>
        ---[ end trace 986a4d314dcb2694 ]---
      Fix the problem by making sure __writeback_single_inode() writes inode
      only with dirty times in WB_SYNC_ALL mode.
      Reported-by: 's avatarDmitry Vyukov <dvyukov@google.com>
      Tested-by: 's avatarLaurent Dufour <ldufour@linux.vnet.ibm.com>
      Signed-off-by: 's avatarJan Kara <jack@suse.cz>
      Signed-off-by: 's avatarJens Axboe <axboe@fb.com>
  11. 28 Jul, 2016 1 commit
  12. 26 Jul, 2016 2 commits
  13. 30 Jun, 2016 1 commit
    • Tahsin Erdogan's avatar
      writeback: inode cgroup wb switch should not call ihold() · 74524955
      Tahsin Erdogan authored
      Asynchronous wb switching of inodes takes an additional ref count on an
      inode to make sure inode remains valid until switchover is completed.
      However, anyone calling ihold() must already have a ref count on inode,
      but in this case inode->i_count may already be zero:
      ------------[ cut here ]------------
      WARNING: CPU: 1 PID: 917 at fs/inode.c:397 ihold+0x2b/0x30
      CPU: 1 PID: 917 Comm: kworker/u4:5 Not tainted 4.7.0-rc2+ #49
      Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs
      Workqueue: writeback wb_workfn (flush-8:16)
       0000000000000000 ffff88007ca0fb58 ffffffff805990af 0000000000000000
       0000000000000000 ffff88007ca0fb98 ffffffff80268702 0000018d000004e2
       ffff88007cef40e8 ffff88007c9b89a8 ffff880079e3a740 0000000000000003
      Call Trace:
       [<ffffffff805990af>] dump_stack+0x4d/0x6e
       [<ffffffff80268702>] __warn+0xc2/0xe0
       [<ffffffff802687d8>] warn_slowpath_null+0x18/0x20
       [<ffffffff8035b4ab>] ihold+0x2b/0x30
       [<ffffffff80367ecc>] inode_switch_wbs+0x11c/0x180
       [<ffffffff80369110>] wbc_detach_inode+0x170/0x1a0
       [<ffffffff80369abc>] writeback_sb_inodes+0x21c/0x530
       [<ffffffff80369f7e>] wb_writeback+0xee/0x1e0
       [<ffffffff8036a147>] wb_workfn+0xd7/0x280
       [<ffffffff80287531>] ? try_to_wake_up+0x1b1/0x2b0
       [<ffffffff8027bb09>] process_one_work+0x129/0x300
       [<ffffffff8027be06>] worker_thread+0x126/0x480
       [<ffffffff8098cde7>] ? __schedule+0x1c7/0x561
       [<ffffffff8027bce0>] ? process_one_work+0x300/0x300
       [<ffffffff80280ff4>] kthread+0xc4/0xe0
       [<ffffffff80335578>] ? kfree+0xc8/0x100
       [<ffffffff809903cf>] ret_from_fork+0x1f/0x40
       [<ffffffff80280f30>] ? __kthread_parkme+0x70/0x70
      ---[ end trace aaefd2fd9f306bc4 ]---
      Signed-off-by: 's avatarTahsin Erdogan <tahsin@google.com>
      Acked-by: 's avatarTejun Heo <tj@kernel.org>
      Reviewed-by: 's avatarJan Kara <jack@suse.cz>
      Signed-off-by: 's avatarJens Axboe <axboe@fb.com>
  14. 21 May, 2016 1 commit
    • Tetsuo Handa's avatar
      mm,writeback: don't use memory reserves for wb_start_writeback · 78ebc2f7
      Tetsuo Handa authored
      When writeback operation cannot make forward progress because memory
      allocation requests needed for doing I/O cannot be satisfied (e.g.
      under OOM-livelock situation), we can observe flood of order-0 page
      allocation failure messages caused by complete depletion of memory
      This is caused by unconditionally allocating "struct wb_writeback_work"
      objects using GFP_ATOMIC from PF_MEMALLOC context.
      __alloc_pages_nodemask() {
        __alloc_pages_slowpath() {
          __alloc_pages_direct_reclaim() {
            __perform_reclaim() {
              current->flags |= PF_MEMALLOC;
              try_to_free_pages() {
                do_try_to_free_pages() {
                  wakeup_flusher_threads() {
                    wb_start_writeback() {
                      kzalloc(sizeof(*work), GFP_ATOMIC) {
                        /* ALLOC_NO_WATERMARKS via PF_MEMALLOC */
              current->flags &= ~PF_MEMALLOC;
      Since I/O is stalling, allocating writeback requests forever shall
      deplete memory reserves.  Fortunately, since wb_start_writeback() can
      fall back to wb_wakeup() when allocating "struct wb_writeback_work"
      failed, we don't need to allow wb_start_writeback() to use memory
        active_anon:289393 inactive_anon:2093 isolated_anon:29
         active_file:10838 inactive_file:113013 isolated_file:859
         unevictable:0 dirty:108531 writeback:5308 unstable:0
         slab_reclaimable:5526 slab_unreclaimable:7077
         mapped:9970 shmem:2159 pagetables:2387 bounce:0
         free:3042 free_pcp:0 free_cma:0
        Node 0 DMA free:6968kB min:44kB low:52kB high:64kB active_anon:6056kB inactive_anon:176kB active_file:712kB inactive_file:744kB unevictable:0kB isolated(anon):0kB isolated(file):0kB present:15988kB managed:15904kB mlocked:0kB dirty:756kB writeback:0kB mapped:736kB shmem:184kB slab_reclaimable:48kB slab_unreclaimable:208kB kernel_stack:160kB pagetables:144kB unstable:0kB bounce:0kB free_pcp:0kB local_pcp:0kB free_cma:0kB writeback_tmp:0kB pages_scanned:9708 all_unreclaimable? yes
        lowmem_reserve[]: 0 1732 1732 1732
        Node 0 DMA32 free:5200kB min:5200kB low:6500kB high:7800kB active_anon:1151516kB inactive_anon:8196kB active_file:42640kB inactive_file:451076kB unevictable:0kB isolated(anon):116kB isolated(file):3564kB present:2080640kB managed:1775332kB mlocked:0kB dirty:433368kB writeback:21232kB mapped:39144kB shmem:8452kB slab_reclaimable:22056kB slab_unreclaimable:28100kB kernel_stack:20976kB pagetables:9404kB unstable:0kB bounce:0kB free_pcp:120kB local_pcp:0kB free_cma:0kB writeback_tmp:0kB pages_scanned:2701604 all_unreclaimable? no
        lowmem_reserve[]: 0 0 0 0
        Node 0 DMA: 25*4kB (UME) 16*8kB (UME) 3*16kB (UE) 5*32kB (UME) 2*64kB (UM) 2*128kB (ME) 2*256kB (ME) 1*512kB (E) 1*1024kB (E) 2*2048kB (ME) 0*4096kB = 6964kB
        Node 0 DMA32: 925*4kB (UME) 140*8kB (UME) 5*16kB (ME) 5*32kB (M) 0*64kB 0*128kB 0*256kB 0*512kB 0*1024kB 0*2048kB 0*4096kB = 5060kB
        Node 0 hugepages_total=0 hugepages_free=0 hugepages_surp=0 hugepages_size=1048576kB
        Node 0 hugepages_total=0 hugepages_free=0 hugepages_surp=0 hugepages_size=2048kB
        126847 total pagecache pages
        0 pages in swap cache
        Swap cache stats: add 0, delete 0, find 0/0
        Free swap  = 0kB
        Total swap = 0kB
        524157 pages RAM
        0 pages HighMem/MovableOnly
        76348 pages reserved
        0 pages hwpoisoned
        Out of memory: Kill process 4450 (file_io.00) score 998 or sacrifice child
        Killed process 4450 (file_io.00) total-vm:4308kB, anon-rss:100kB, file-rss:1184kB, shmem-rss:0kB
        kthreadd: page allocation failure: order:0, mode:0x2200020
        file_io.00: page allocation failure: order:0, mode:0x2200020
        CPU: 0 PID: 4457 Comm: file_io.00 Not tainted 4.5.0-rc7+ #45
        Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform, BIOS 6.00 07/31/2013
        Call Trace:
        active_anon:293335 inactive_anon:2093 isolated_anon:0
         active_file:10829 inactive_file:110045 isolated_file:32
         unevictable:0 dirty:109275 writeback:822 unstable:0
         slab_reclaimable:5489 slab_unreclaimable:10070
         mapped:9999 shmem:2159 pagetables:2420 bounce:0
         free:3 free_pcp:0 free_cma:0
        Node 0 DMA free:12kB min:44kB low:52kB high:64kB active_anon:6060kB inactive_anon:176kB active_file:708kB inactive_file:756kB unevictable:0kB isolated(anon):0kB isolated(file):0kB present:15988kB managed:15904kB mlocked:0kB dirty:756kB writeback:0kB mapped:736kB shmem:184kB slab_reclaimable:48kB slab_unreclaimable:7160kB kernel_stack:160kB pagetables:144kB unstable:0kB bounce:0kB free_pcp:0kB local_pcp:0kB free_cma:0kB writeback_tmp:0kB pages_scanned:9844 all_unreclaimable? yes
        lowmem_reserve[]: 0 1732 1732 1732
        Node 0 DMA32 free:0kB min:5200kB low:6500kB high:7800kB active_anon:1167280kB inactive_anon:8196kB active_file:42608kB inactive_file:439424kB unevictable:0kB isolated(anon):0kB isolated(file):128kB present:2080640kB managed:1775332kB mlocked:0kB dirty:436344kB writeback:3288kB mapped:39260kB shmem:8452kB slab_reclaimable:21908kB slab_unreclaimable:33120kB kernel_stack:20976kB pagetables:9536kB unstable:0kB bounce:0kB free_pcp:0kB local_pcp:0kB free_cma:0kB writeback_tmp:0kB pages_scanned:11073180 all_unreclaimable? yes
        lowmem_reserve[]: 0 0 0 0
        Node 0 DMA: 0*4kB 0*8kB 0*16kB 0*32kB 0*64kB 0*128kB 0*256kB 0*512kB 0*1024kB 0*2048kB 0*4096kB = 0kB
        Node 0 DMA32: 0*4kB 0*8kB 0*16kB 0*32kB 0*64kB 0*128kB 0*256kB 0*512kB 0*1024kB 0*2048kB 0*4096kB = 0kB
        Node 0 hugepages_total=0 hugepages_free=0 hugepages_surp=0 hugepages_size=1048576kB
        Node 0 hugepages_total=0 hugepages_free=0 hugepages_surp=0 hugepages_size=2048kB
        123086 total pagecache pages
        0 pages in swap cache
        Swap cache stats: add 0, delete 0, find 0/0
        Free swap  = 0kB
        Total swap = 0kB
        524157 pages RAM
        0 pages HighMem/MovableOnly
        76348 pages reserved
        0 pages hwpoisoned
        SLUB: Unable to allocate memory on node -1 (gfp=0x2088020)
          cache: kmalloc-64, object size: 64, buffer size: 64, default order: 0, min order: 0
          node 0: slabs: 3218, objs: 205952, free: 0
        file_io.00: page allocation failure: order:0, mode:0x2200020
        CPU: 0 PID: 4457 Comm: file_io.00 Not tainted 4.5.0-rc7+ #45
      Assuming that somebody will find a better solution, let's apply this
      patch for now to stop bleeding, for this problem frequently prevents me
      from testing OOM livelock condition.
      Link: http://lkml.kernel.org/r/20160318131136.GE7152@quack.suse.czSigned-off-by: 's avatarTetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
      Acked-by: 's avatarMichal Hocko <mhocko@suse.com>
      Cc: Jan Kara <jack@suse.cz>
      Cc: Tejun Heo <tj@kernel.org>
      Signed-off-by: 's avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: 's avatarLinus Torvalds <torvalds@linux-foundation.org>
  15. 04 Apr, 2016 1 commit
    • Kirill A. Shutemov's avatar
      mm, fs: get rid of PAGE_CACHE_* and page_cache_{get,release} macros · 09cbfeaf
      Kirill A. Shutemov authored
      PAGE_CACHE_{SIZE,SHIFT,MASK,ALIGN} macros were introduced *long* time
      ago with promise that one day it will be possible to implement page
      cache with bigger chunks than PAGE_SIZE.
      This promise never materialized.  And unlikely will.
      We have many places where PAGE_CACHE_SIZE assumed to be equal to
      PAGE_SIZE.  And it's constant source of confusion on whether
      PAGE_CACHE_* or PAGE_* constant should be used in a particular case,
      especially on the border between fs and mm.
      Global switching to PAGE_CACHE_SIZE != PAGE_SIZE would cause to much
      breakage to be doable.
      Let's stop pretending that pages in page cache are special.  They are
      The changes are pretty straight-forward:
       - <foo> << (PAGE_CACHE_SHIFT - PAGE_SHIFT) -> <foo>;
       - <foo> >> (PAGE_CACHE_SHIFT - PAGE_SHIFT) -> <foo>;
       - page_cache_get() -> get_page();
       - page_cache_release() -> put_page();
      This patch contains automated changes generated with coccinelle using
      script below.  For some reason, coccinelle doesn't patch header files.
      I've called spatch for them manually.
      The only adjustment after coccinelle is revert of changes to
      PAGE_CAHCE_ALIGN definition: we are going to drop it later.
      There are few places in the code where coccinelle didn't reach.  I'll
      fix them manually in a separate patch.  Comments and documentation also
      will be addressed with the separate patch.
      virtual patch
      expression E;
      + E
      expression E;
      + E
      + PAGE_SHIFT
      + PAGE_SIZE
      + PAGE_MASK
      expression E;
      + PAGE_ALIGN(E)
      expression E;
      - page_cache_get(E)
      + get_page(E)
      expression E;
      - page_cache_release(E)
      + put_page(E)
      Signed-off-by: 's avatarKirill A. Shutemov <kirill.shutemov@linux.intel.com>
      Acked-by: 's avatarMichal Hocko <mhocko@suse.com>
      Signed-off-by: 's avatarLinus Torvalds <torvalds@linux-foundation.org>
  16. 20 Mar, 2016 2 commits
    • Tejun Heo's avatar
      writeback, cgroup: fix use of the wrong bdi_writeback which mismatches the inode · aaf25593
      Tejun Heo authored
      When cgroup writeback is in use, there can be multiple wb's
      (bdi_writeback's) per bdi and an inode may switch among them
      dynamically.  In a couple places, the wrong wb was used leading to
      performing operations on the wrong list under the wrong lock
      corrupting the io lists.
      * writeback_single_inode() was taking @wb parameter and used it to
        remove the inode from io lists if it becomes clean after writeback.
        The callers of this function were always passing in the root wb
        regardless of the actual wb that the inode was associated with,
        which could also change while writeback is in progress.
        Fix it by dropping the @wb parameter and using
        inode_to_wb_and_lock_list() to determine and lock the associated wb.
      * After writeback_sb_inodes() writes out an inode, it re-locks @wb and
        inode to remove it from or move it to the right io list.  It assumes
        that the inode is still associated with @wb; however, the inode may
        have switched to another wb while writeback was in progress.
        Fix it by using inode_to_wb_and_lock_list() to determine and lock
        the associated wb after writeback is complete.  As the function
        requires the original @wb->list_lock locked for the next iteration,
        in the unlikely case where the inode has changed association, switch
        the locks.
      Kudos to Tahsin for pinpointing these subtle breakages.
      Signed-off-by: 's avatarTejun Heo <tj@kernel.org>
      Fixes: d10c8095 ("writeback: implement foreign cgroup inode bdi_writeback switching")
      Link: http://lkml.kernel.org/g/CAAeU0aMYeM_39Y2+PaRvyB1nqAPYZSNngJ1eBRmrxn7gKAt2Mg@mail.gmail.comReported-and-diagnosed-by: 's avatarTahsin Erdogan <tahsin@google.com>
      Tested-by: 's avatarTahsin Erdogan <tahsin@google.com>
      Cc: stable@vger.kernel.org # v4.2+
      Signed-off-by: 's avatarJens Axboe <axboe@fb.com>
    • Tejun Heo's avatar
      writeback, cgroup: fix premature wb_put() in locked_inode_to_wb_and_lock_list() · 614a4e37
      Tejun Heo authored
      locked_inode_to_wb_and_lock_list() wb_get()'s the wb associated with
      the target inode, unlocks inode, locks the wb's list_lock and verifies
      that the inode is still associated with the wb.  To prevent the wb
      going away between dropping inode lock and acquiring list_lock, the wb
      is pinned while inode lock is held.  The wb reference is put right
      after acquiring list_lock citing that the wb won't be dereferenced
      This isn't true.  If the inode is still associated with the wb, the
      inode has reference and it's safe to return the wb; however, if inode
      has been switched, the wb still needs to be unlocked which is a
      dereference and can lead to use-after-free if it it races with wb
      Fix it by putting the reference after releasing list_lock.
      Signed-off-by: 's avatarTejun Heo <tj@kernel.org>
      Fixes: 87e1d789 ("writeback: implement [locked_]inode_to_wb_and_lock_list()")
      Cc: stable@vger.kernel.org # v4.2+
      Tested-by: 's avatarTahsin Erdogan <tahsin@google.com>
      Signed-off-by: 's avatarJens Axboe <axboe@fb.com>
  17. 03 Mar, 2016 1 commit
    • Tejun Heo's avatar
      writeback: flush inode cgroup wb switches instead of pinning super_block · a1a0e23e
      Tejun Heo authored
      If cgroup writeback is in use, inodes can be scheduled for
      asynchronous wb switching.  Before 5ff8eaac ("writeback: keep
      superblock pinned during cgroup writeback association switches"), this
      could race with umount leading to super_block being destroyed while
      inodes are pinned for wb switching.  5ff8eaac fixed it by bumping
      s_active while wb switches are in flight; however, this allowed
      in-flight wb switches to make umounts asynchronous when the userland
      expected synchronosity - e.g. fsck immediately following umount may
      fail because the device is still busy.
      This patch removes the problematic super_block pinning and instead
      makes generic_shutdown_super() flush in-flight wb switches.  wb
      switches are now executed on a dedicated isw_wq so that they can be
      flushed and isw_nr_in_flight keeps track of the number of in-flight wb
      switches so that flushing can be avoided in most cases.
      v2: Move cgroup_writeback_umount() further below and add MS_ACTIVE
          check in inode_switch_wbs() as Jan an Al suggested.
      Signed-off-by: 's avatarTejun Heo <tj@kernel.org>
      Reported-by: 's avatarTahsin Erdogan <tahsin@google.com>
      Cc: Jan Kara <jack@suse.cz>
      Cc: Al Viro <viro@ZenIV.linux.org.uk>
      Link: http://lkml.kernel.org/g/CAAeU0aNCq7LGODvVGRU-oU_o-6enii5ey0p1c26D1ZzYwkDc5A@mail.gmail.com
      Fixes: 5ff8eaac ("writeback: keep superblock pinned during cgroup writeback association switches")
      Cc: stable@vger.kernel.org #v4.5
      Reviewed-by: 's avatarJan Kara <jack@suse.cz>
      Tested-by: 's avatarTahsin Erdogan <tahsin@google.com>
      Signed-off-by: 's avatarJens Axboe <axboe@fb.com>
  18. 16 Feb, 2016 1 commit
    • Tejun Heo's avatar
      writeback: keep superblock pinned during cgroup writeback association switches · 5ff8eaac
      Tejun Heo authored
      If cgroup writeback is in use, an inode is associated with a cgroup
      for writeback.  If the inode's main dirtier changes to another cgroup,
      the association gets updated asynchronously.  Nothing was pinning the
      superblock while such switches are in progress and superblock could go
      away while async switching is pending or in progress leading to
      crashes like the following.
       kernel BUG at fs/jbd2/transaction.c:319!
       invalid opcode: 0000 [#1] SMP DEBUG_PAGEALLOC
       CPU: 1 PID: 29158 Comm: kworker/1:10 Not tainted 4.5.0-rc3 #51
       Hardware name: Google Google, BIOS Google 01/01/2011
       Workqueue: events inode_switch_wbs_work_fn
       task: ffff880213dbbd40 ti: ffff880209264000 task.ti: ffff880209264000
       RIP: 0010:[<ffffffff803e6922>]  [<ffffffff803e6922>] start_this_handle+0x382/0x3e0
       RSP: 0018:ffff880209267c30  EFLAGS: 00010202
       Call Trace:
        [<ffffffff803e6be4>] jbd2__journal_start+0xf4/0x190
        [<ffffffff803cfc7e>] __ext4_journal_start_sb+0x4e/0x70
        [<ffffffff803b31ec>] ext4_evict_inode+0x12c/0x3d0
        [<ffffffff8035338b>] evict+0xbb/0x190
        [<ffffffff80354190>] iput+0x130/0x190
        [<ffffffff80360223>] inode_switch_wbs_work_fn+0x343/0x4c0
        [<ffffffff80279819>] process_one_work+0x129/0x300
        [<ffffffff80279b16>] worker_thread+0x126/0x480
        [<ffffffff8027ed14>] kthread+0xc4/0xe0
        [<ffffffff809771df>] ret_from_fork+0x3f/0x70
      Fix it by bumping s_active while cgroup association switching is in
      Signed-off-by: 's avatarTejun Heo <tj@kernel.org>
      Reported-and-tested-by: 's avatarTahsin Erdogan <tahsin@google.com>
      Link: http://lkml.kernel.org/g/CAAeU0aNCq7LGODvVGRU-oU_o-6enii5ey0p1c26D1ZzYwkDc5A@mail.gmail.com
      Fixes: d10c8095 ("writeback: implement foreign cgroup inode bdi_writeback switching")
      Cc: stable@vger.kernel.org #v4.5+
      Signed-off-by: 's avatarJens Axboe <axboe@fb.com>
  19. 16 Jan, 2016 1 commit
  20. 11 Nov, 2015 1 commit
  21. 09 Nov, 2015 1 commit
  22. 06 Nov, 2015 1 commit
    • Junichi Nomura's avatar
      mm/filemap.c: make global sync not clear error status of individual inodes · aa750fd7
      Junichi Nomura authored
      filemap_fdatawait() is a function to wait for on-going writeback to
      complete but also consume and clear error status of the mapping set during
      The latter functionality is critical for applications to detect writeback
      error with system calls like fsync(2)/fdatasync(2).
      However filemap_fdatawait() is also used by sync(2) or FIFREEZE ioctl,
      which don't check error status of individual mappings.
      As a result, fsync() may not be able to detect writeback error if events
      happen in the following order:
         Application                    System admin
         write data on page cache
                                        Run sync command
                                        writeback completes with error
                                        filemap_fdatawait() clears error
         fsync returns success
         (but the data is not on disk)
      This patch adds filemap_fdatawait_keep_errors() for call sites where
      writeback error is not handled so that they don't clear error status.
      Signed-off-by: 's avatarJun'ichi Nomura <j-nomura@ce.jp.nec.com>
      Acked-by: 's avatarAndi Kleen <ak@linux.intel.com>
      Reviewed-by: 's avatarTejun Heo <tj@kernel.org>
      Cc: Fengguang Wu <fengguang.wu@gmail.com>
      Cc: Dave Chinner <david@fromorbit.com>
      Signed-off-by: 's avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: 's avatarLinus Torvalds <torvalds@linux-foundation.org>
  23. 28 Oct, 2015 1 commit
    • Tejun Heo's avatar
      fs/writeback, rcu: Don't use list_entry_rcu() for pointer offsetting in bdi_split_work_to_wbs() · b33e18f6
      Tejun Heo authored
      bdi_split_work_to_wbs() uses list_for_each_entry_rcu_continue()
      to walk @bdi->wb_list.  To set up the initial iteration
      condition, it uses list_entry_rcu() to calculate the entry
      pointer corresponding to the list head; however, this isn't an
      actual RCU dereference and using list_entry_rcu() for it ended
      up breaking a proposed list_entry_rcu() change because it was
      feeding an non-lvalue pointer into the macro.
      Don't use the RCU variant for simple pointer offsetting.  Use
      list_entry() instead.
      Reported-by: 's avatarIngo Molnar <mingo@kernel.org>
      Signed-off-by: 's avatarTejun Heo <tj@kernel.org>
      Cc: Darren Hart <dvhart@linux.intel.com>
      Cc: David Howells <dhowells@redhat.com>
      Cc: Dipankar Sarma <dipankar@in.ibm.com>
      Cc: Eric Dumazet <edumazet@google.com>
      Cc: Frederic Weisbecker <fweisbec@gmail.com>
      Cc: Josh Triplett <josh@joshtriplett.org>
      Cc: Lai Jiangshan <jiangshanlai@gmail.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
      Cc: Oleg Nesterov <oleg@redhat.com>
      Cc: Patrick Marlier <patrick.marlier@gmail.com>
      Cc: Paul McKenney <paulmck@linux.vnet.ibm.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Steven Rostedt <rostedt@goodmis.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: pranith kumar <bobby.prani@gmail.com>
      Link: http://lkml.kernel.org/r/20151027051939.GA19355@mtj.duckdns.orgSigned-off-by: 's avatarIngo Molnar <mingo@kernel.org>
  24. 12 Oct, 2015 2 commits
    • Tejun Heo's avatar
      writeback: bdi_writeback iteration must not skip dying ones · b817525a
      Tejun Heo authored
      bdi_for_each_wb() is used in several places to wake up or issue
      writeback work items to all wb's (bdi_writeback's) on a given bdi.
      The iteration is performed by walking bdi->cgwb_tree; however, the
      tree only indexes wb's which are currently active.
      For example, when a memcg gets associated with a different blkcg, the
      old wb is removed from the tree so that the new one can be indexed.
      The old wb starts dying from then on but will linger till all its
      inodes are drained.  As these dying wb's may still host dirty inodes,
      writeback operations which affect all wb's must include them.
      bdi_for_each_wb() skipping dying wb's led to sync(2) missing and
      failing to sync the inodes belonging to those wb's.
      This patch adds a RCU protected @bdi->wb_list which lists all wb's
      beloinging to that bdi.  wb's are added on creation and removed on
      release rather than on the start of destruction.  bdi_for_each_wb()
      usages are replaced with list_for_each[_continue]_rcu() iterations
      over @bdi->wb_list and bdi_for_each_wb() and its helpers are removed.
      v2: Updated as per Jan.  last_wb ref leak in bdi_split_work_to_wbs()
          fixed and unnecessary list head severing in cgwb_bdi_destroy()
      Signed-off-by: 's avatarTejun Heo <tj@kernel.org>
      Reported-and-tested-by: 's avatarArtem Bityutskiy <dedekind1@gmail.com>
      Fixes: ebe41ab0 ("writeback: implement bdi_for_each_wb()")
      Link: http://lkml.kernel.org/g/1443012552.19983.209.camel@gmail.com
      Cc: Jan Kara <jack@suse.cz>
      Signed-off-by: 's avatarJens Axboe <axboe@fb.com>
    • Tejun Heo's avatar
      writeback: fix bdi_writeback iteration in wakeup_dirtytime_writeback() · 6fdf860f
      Tejun Heo authored
      wakeup_dirtytime_writeback() walks and wakes up all wb's of all bdi's;
      unfortunately, it was always waking up bdi->wb instead of the wb being
      walked.  Fix it.
      Signed-off-by: 's avatarTejun Heo <tj@kernel.org>
      Fixes: 001fe6f6 ("writeback: make wakeup_dirtytime_writeback() handle multiple bdi_writeback's")
      Reviewed-by: 's avatarJan Kara <jack@suse.com>
      Signed-off-by: 's avatarJens Axboe <axboe@fb.com>
  25. 20 Sep, 2015 1 commit
    • Chris Mason's avatar
      fs-writeback: unplug before cond_resched in writeback_sb_inodes · 590dca3a
      Chris Mason authored
      Commit 505a666e ("writeback: plug writeback in wb_writeback() and
      writeback_inodes_wb()") has us holding a plug during writeback_sb_inodes,
      which increases the merge rate when relatively contiguous small files
      are written by the filesystem.  It helps both on flash and spindles.
      For an fs_mark workload creating 4K files in parallel across 8 drives,
      this commit improves performance ~9% more by unplugging before calling
      cond_resched().  cond_resched() doesn't trigger an implicit unplug, so
      explicitly getting the IO down to the device before scheduling reduces
      latencies for anyone waiting on clean pages.
      It also cuts down on how often we use kblockd to unplug, which means
      less work bouncing from one workqueue to another.
      Many more details about how we got here:
        https://lkml.org/lkml/2015/9/11/570Signed-off-by: 's avatarChris Mason <clm@fb.com>
      Signed-off-by: 's avatarLinus Torvalds <torvalds@linux-foundation.org>
  26. 12 Sep, 2015 1 commit
    • Linus Torvalds's avatar
      writeback: plug writeback in wb_writeback() and writeback_inodes_wb() · 505a666e
      Linus Torvalds authored
      We had to revert the pluggin in writeback_sb_inodes() because the
      wb->list_lock is held, but we could easily plug at a higher level before
      taking that lock, and unplug after releasing it.  This does that.
      Chris will run performance numbers, just to verify that this approach is
      comparable to the alternative (we could just drop and re-take the lock
      around the blk_finish_plug() rather than these two commits.
      I'd have preferred waiting for actual performance numbers before picking
      one approach over the other, but I don't want to release rc1 with the
      known "sleeping function called from invalid context" issue, so I'll
      pick this cleanup version for now.  But if the numbers show that we
      really want to plug just at the writeback_sb_inodes() level, and we
      should just play ugly games with the spinlock, we'll switch to that.
      Cc: Chris Mason <clm@fb.com>
      Cc: Josef Bacik <jbacik@fb.com>
      Cc: Dave Chinner <david@fromorbit.com>
      Cc: Neil Brown <neilb@suse.de>
      Cc: Jan Kara <jack@suse.cz>
      Cc: Christoph Hellwig <hch@lst.de>
      Signed-off-by: 's avatarLinus Torvalds <torvalds@linux-foundation.org>
  27. 11 Sep, 2015 1 commit
    • Linus Torvalds's avatar
      Revert "writeback: plug writeback at a high level" · 0ba13fd1
      Linus Torvalds authored
      This reverts commit d353d758.
      Doing the block layer plug/unplug inside writeback_sb_inodes() is
      broken, because that function is actually called with a spinlock held:
      wb->list_lock, as pointed out by Chris Mason.
      Chris suggested just dropping and re-taking the spinlock around the
      blk_finish_plug() call (the plgging itself can happen under the
      spinlock), and that would technically work, but is just disgusting.
      We do something fairly similar - but not quite as disgusting because we
      at least have a better reason for it - in writeback_single_inode(), so
      it's not like the caller can depend on the lock being held over the
      call, but in this case there just isn't any good reason for that
      "release and re-take the lock" pattern.
      [ In general, we should really strive to avoid the "release and retake"
        pattern for locks, because in the general case it can easily cause
        subtle bugs when the caller caches any state around the call that
        might be invalidated by dropping the lock even just temporarily. ]
      But in this case, the plugging should be easy to just move up to the
      callers before the spinlock is taken, which should even improve the
      effectiveness of the plug.  So there is really no good reason to play
      games with locking here.
      I'll send off a test-patch so that Dave Chinner can verify that that
      plug movement works.  In the meantime this just reverts the problematic
      commit and adds a comment to the function so that we hopefully don't
      make this mistake again.
      Reported-by: 's avatarChris Mason <clm@fb.com>
      Cc: Josef Bacik <jbacik@fb.com>
      Cc: Dave Chinner <david@fromorbit.com>
      Cc: Neil Brown <neilb@suse.de>
      Cc: Jan Kara <jack@suse.cz>
      Cc: Christoph Hellwig <hch@lst.de>
      Signed-off-by: 's avatarLinus Torvalds <torvalds@linux-foundation.org>
  28. 25 Aug, 2015 1 commit
    • Tejun Heo's avatar
      writeback: sync_inodes_sb() must write out I_DIRTY_TIME inodes and always call wait_sb_inodes() · 006a0973
      Tejun Heo authored
      e7972912 ("writeback: don't issue wb_writeback_work if clean")
      updated writeback path to avoid kicking writeback work items if there
      are no inodes to be written out; unfortunately, the avoidance logic
      was too aggressive and broke sync_inodes_sb().
      * sync_inodes_sb() must write out I_DIRTY_TIME inodes but I_DIRTY_TIME
        inodes dont't contribute to bdi/wb_has_dirty_io() tests and were
        being skipped over.
      * inodes are taken off wb->b_dirty/io/more_io lists after writeback
        starts on them.  sync_inodes_sb() skipping wait_sb_inodes() when
        bdi_has_dirty_io() breaks it by making it return while writebacks
        are in-flight.
      This patch fixes the breakages by
      * Removing bdi_has_dirty_io() shortcut from bdi_split_work_to_wbs().
        The callers are already testing the condition.
      * Removing bdi_has_dirty_io() shortcut from sync_inodes_sb() so that
        it always calls into bdi_split_work_to_wbs() and wait_sb_inodes().
      * Making bdi_split_work_to_wbs() consider the b_dirty_time list for
        WB_SYNC_ALL writebacks.
      Kudos to Eryu, Dave and Jan for tracking down the issue.
      Signed-off-by: 's avatarTejun Heo <tj@kernel.org>
      Fixes: e7972912 ("writeback: don't issue wb_writeback_work if clean")
      Link: http://lkml.kernel.org/g/20150812101204.GE17933@dhcp-13-216.nay.redhat.comReported-and-bisected-by: 's avatarEryu Guan <eguan@redhat.com>
      Cc: Dave Chinner <david@fromorbit.com>
      Cc: Jan Kara <jack@suse.com>
      Cc: Ted Ts'o <tytso@google.com>
      Signed-off-by: 's avatarJens Axboe <axboe@fb.com>
  29. 18 Aug, 2015 3 commits