1. 14 5月, 2018 1 次提交
    • D
      afs: Fix whole-volume callback handling · 68251f0a
      David Howells 提交于
      It's possible for an AFS file server to issue a whole-volume notification
      that callbacks on all the vnodes in the file have been broken.  This is
      done for R/O and backup volumes (which don't have per-file callbacks) and
      for things like a volume being taken offline.
      
      Fix callback handling to detect whole-volume notifications, to track it
      across operations and to check it during inode validation.
      
      Fixes: c435ee34 ("afs: Overhaul the callback handling")
      Signed-off-by: NDavid Howells <dhowells@redhat.com>
      68251f0a
  2. 10 4月, 2018 3 次提交
    • D
      afs: Do better accretion of small writes on newly created content · 5a813276
      David Howells 提交于
      Processes like ld that do lots of small writes that aren't necessarily
      contiguous result in a lot of small StoreData operations to the server, the
      idea being that if someone else changes the data on the server, we only
      write our changes over that and not the space between.  Further, we don't
      want to write back empty space if we can avoid it to make it easier for the
      server to do sparse files.
      
      However, making lots of tiny RPC ops is a lot less efficient for the server
      than one big one because each op requires allocation of resources and the
      taking of locks, so we want to compromise a bit.
      
      Reduce the load by the following:
      
       (1) If a file is just created locally or has just been truncated with
           O_TRUNC locally, allow subsequent writes to the file to be merged with
           intervening space if that space doesn't cross an entire intervening
           page.
      
       (2) Don't flush the file on ->flush() but rather on ->release() if the
           file was open for writing.
      
      Just linking vmlinux.o, without this patch, looking in /proc/fs/afs/stats:
      
      	file-wr : n=441 nb=513581204
      
      and after the patch:
      
      	file-wr : n=62 nb=513668555
      
      there were 379 fewer StoreData RPC operations at the expense of an extra
      87K being written.
      Signed-off-by: NDavid Howells <dhowells@redhat.com>
      5a813276
    • D
      afs: Add stats for data transfer operations · 76a5cb6f
      David Howells 提交于
      Add statistics to /proc/fs/afs/stats for data transfer RPC operations.  New
      lines are added that look like:
      
      	file-rd : n=55794 nb=10252282150
      	file-wr : n=9789 nb=3247763645
      
      where n= indicates the number of ops completed and nb= indicates the number
      of bytes successfully transferred.  file-rd is the counts for read/fetch
      operations and file-wr the counts for write/store operations.
      
      Note that directory and symlink downloading are included in the file-rd
      stats at the moment.
      Signed-off-by: NDavid Howells <dhowells@redhat.com>
      76a5cb6f
    • D
      afs: Fix directory handling · f3ddee8d
      David Howells 提交于
      AFS directories are structured blobs that are downloaded just like files
      and then parsed by the lookup and readdir code and, as such, are currently
      handled in the pagecache like any other file, with the entire directory
      content being thrown away each time the directory changes.
      
      However, since the blob is a known structure and since the data version
      counter on a directory increases by exactly one for each change committed
      to that directory, we can actually edit the directory locally rather than
      fetching it from the server after each locally-induced change.
      
      What we can't do, though, is mix data from the server and data from the
      client since the server is technically at liberty to rearrange or compress
      a directory if it sees fit, provided it updates the data version number
      when it does so and breaks the callback (ie. sends a notification).
      
      Further, lookup with lookup-ahead, readdir and, when it arrives, local
      editing are likely want to scan the whole of a directory.
      
      So directory handling needs to be improved to maintain the coherency of the
      directory blob prior to permitting local directory editing.
      
      To this end:
      
       (1) If any directory page gets discarded, invalidate and reread the entire
           directory.
      
       (2) If readpage notes that if when it fetches a single page that the
           version number has changed, the entire directory is flagged for
           invalidation.
      
       (3) Read as much of the directory in one go as we can.
      
      Note that this removes local caching of directories in fscache for the
      moment as we can't pass the pages to fscache_read_or_alloc_pages() since
      page->lru is in use by the LRU.
      Signed-off-by: NDavid Howells <dhowells@redhat.com>
      f3ddee8d
  3. 06 4月, 2018 1 次提交
  4. 13 11月, 2017 7 次提交
    • D
      afs: Trace page dirty/clean · 13524ab3
      David Howells 提交于
      Add a trace event that logs the dirtying and cleaning of pages attached to
      AFS inodes.
      Signed-off-by: NDavid Howells <dhowells@redhat.com>
      13524ab3
    • D
      afs: Implement shared-writeable mmap · 1cf7a151
      David Howells 提交于
      Implement shared-writeable mmap for AFS.
      Signed-off-by: NDavid Howells <dhowells@redhat.com>
      1cf7a151
    • D
      afs: Get rid of the afs_writeback record · 4343d008
      David Howells 提交于
      Get rid of the afs_writeback record that kAFS is using to match keys with
      writes made by that key.
      
      Instead, keep a list of keys that have a file open for writing and/or
      sync'ing and iterate through those.
      Signed-off-by: NDavid Howells <dhowells@redhat.com>
      4343d008
    • D
      afs: Introduce a file-private data record · 215804a9
      David Howells 提交于
      Introduce a file-private data record for kAFS and put the key into it
      rather than storing the key in file->private_data.
      Signed-off-by: NDavid Howells <dhowells@redhat.com>
      215804a9
    • D
      afs: Fix directory read/modify race · dab17c1a
      David Howells 提交于
      Because parsing of the directory wasn't being done under any sort of lock,
      the pages holding the directory content can get invalidated whilst the
      parsing is ongoing.
      
      Further, the directory page check function gets called outside of the page
      lock, so if the page gets cleared or updated, this may return reports of
      bad magic numbers in the directory page.
      
      Also, the directory may change size whilst checking and parsing are
      ongoing, so more care needs to be taken here.
      
      Fix this by:
      
       (1) Perform the page check from the page filling function before we set
           PageUptodate and drop the page lock.
      
       (2) Check for the file having shrunk and the page having been abandoned
           before checking the page contents.
      
       (3) Lock the page whilst parsing it for the directory iterator.
      
      Whilst we're at it, add a tracepoint to report check failure.
      Signed-off-by: NDavid Howells <dhowells@redhat.com>
      dab17c1a
    • D
      afs: Overhaul volume and server record caching and fileserver rotation · d2ddc776
      David Howells 提交于
      The current code assumes that volumes and servers are per-cell and are
      never shared, but this is not enforced, and, indeed, public cells do exist
      that are aliases of each other.  Further, an organisation can, say, set up
      a public cell and a private cell with overlapping, but not identical, sets
      of servers.  The difference is purely in the database attached to the VL
      servers.
      
      The current code will malfunction if it sees a server in two cells as it
      assumes global address -> server record mappings and that each server is in
      just one cell.
      
      Further, each server may have multiple addresses - and may have addresses
      of different families (IPv4 and IPv6, say).
      
      To this end, the following structural changes are made:
      
       (1) Server record management is overhauled:
      
           (a) Server records are made independent of cell.  The namespace keeps
           	 track of them, volume records have lists of them and each vnode
           	 has a server on which its callback interest currently resides.
      
           (b) The cell record no longer keeps a list of servers known to be in
           	 that cell.
      
           (c) The server records are now kept in a flat list because there's no
           	 single address to sort on.
      
           (d) Server records are now keyed by their UUID within the namespace.
      
           (e) The addresses for a server are obtained with the VL.GetAddrsU
           	 rather than with VL.GetEntryByName, using the server's UUID as a
           	 parameter.
      
           (f) Cached server records are garbage collected after a period of
           	 non-use and are counted out of existence before purging is allowed
           	 to complete.  This protects the work functions against rmmod.
      
           (g) The servers list is now in /proc/fs/afs/servers.
      
       (2) Volume record management is overhauled:
      
           (a) An RCU-replaceable server list is introduced.  This tracks both
           	 servers and their coresponding callback interests.
      
           (b) The superblock is now keyed on cell record and numeric volume ID.
      
           (c) The volume record is now tied to the superblock which mounts it,
           	 and is activated when mounted and deactivated when unmounted.
           	 This makes it easier to handle the cache cookie without causing a
           	 double-use in fscache.
      
           (d) The volume record is loaded from the VLDB using VL.GetEntryByNameU
           	 to get the server UUID list.
      
           (e) The volume name is updated if it is seen to have changed when the
           	 volume is updated (the update is keyed on the volume ID).
      
       (3) The vlocation record is got rid of and VLDB records are no longer
           cached.  Sufficient information is stored in the volume record, though
           an update to a volume record is now no longer shared between related
           volumes (volumes come in bundles of three: R/W, R/O and backup).
      
      and the following procedural changes are made:
      
       (1) The fileserver cursor introduced previously is now fleshed out and
           used to iterate over fileservers and their addresses.
      
       (2) Volume status is checked during iteration, and the server list is
           replaced if a change is detected.
      
       (3) Server status is checked during iteration, and the address list is
           replaced if a change is detected.
      
       (4) The abort code is saved into the address list cursor and -ECONNABORTED
           returned in afs_make_call() if a remote abort happened rather than
           translating the abort into an error message.  This allows actions to
           be taken depending on the abort code more easily.
      
           (a) If a VMOVED abort is seen then this is handled by rechecking the
           	 volume and restarting the iteration.
      
           (b) If a VBUSY, VRESTARTING or VSALVAGING abort is seen then this is
               handled by sleeping for a short period and retrying and/or trying
               other servers that might serve that volume.  A message is also
               displayed once until the condition has cleared.
      
           (c) If a VOFFLINE abort is seen, then this is handled as VBUSY for the
           	 moment.
      
           (d) If a VNOVOL abort is seen, the volume is rechecked in the VLDB to
           	 see if it has been deleted; if not, the fileserver is probably
           	 indicating that the volume couldn't be attached and needs
           	 salvaging.
      
           (e) If statfs() sees one of these aborts, it does not sleep, but
           	 rather returns an error, so as not to block the umount program.
      
       (5) The fileserver iteration functions in vnode.c are now merged into
           their callers and more heavily macroised around the cursor.  vnode.c
           is removed.
      
       (6) Operations on a particular vnode are serialised on that vnode because
           the server will lock that vnode whilst it operates on it, so a second
           op sent will just have to wait.
      
       (7) Fileservers are probed with FS.GetCapabilities before being used.
           This is where service upgrade will be done.
      
       (8) A callback interest on a fileserver is set up before an FS operation
           is performed and passed through to afs_make_call() so that it can be
           set on the vnode if the operation returns a callback.  The callback
           interest is passed through to afs_iget() also so that it can be set
           there too.
      
      In general, record updating is done on an as-needed basis when we try to
      access servers, volumes or vnodes rather than offloading it to work items
      and special threads.
      
      Notes:
      
       (1) Pre AFS-3.4 servers are no longer supported, though this can be added
           back if necessary (AFS-3.4 was released in 1998).
      
       (2) VBUSY is retried forever for the moment at intervals of 1s.
      
       (3) /proc/fs/afs/<cell>/servers no longer exists.
      Signed-off-by: NDavid Howells <dhowells@redhat.com>
      d2ddc776
    • D
      afs: Condense afs_call's reply{,2,3,4} into an array · 97e3043a
      David Howells 提交于
      Condense struct afs_call's reply anchor members - reply{,2,3,4} - into an
      array.
      Signed-off-by: NDavid Howells <dhowells@redhat.com>
      97e3043a
  5. 10 7月, 2017 1 次提交
    • D
      afs: Add metadata xattrs · d3e3b7ea
      David Howells 提交于
      Add xattrs to allow the user to get/set metadata in lieu of having pioctl()
      available.  The following xattrs are now available:
      
       - "afs.cell"
      
         The name of the cell in which the vnode's volume resides.
      
       - "afs.fid"
      
         The volume ID, vnode ID and vnode uniquifier of the file as three hex
         numbers separated by colons.
      
       - "afs.volume"
      
         The name of the volume in which the vnode resides.
      
      For example:
      
      	# getfattr -d -m ".*" /mnt/scratch
      	getfattr: Removing leading '/' from absolute path names
      	# file: mnt/scratch
      	afs.cell="mycell.myorg.org"
      	afs.fid="10000b:1:1"
      	afs.volume="scratch"
      Signed-off-by: NDavid Howells <dhowells@redhat.com>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      d3e3b7ea
  6. 17 3月, 2017 3 次提交
  7. 17 1月, 2017 1 次提交
  8. 07 1月, 2017 2 次提交
  9. 05 4月, 2016 1 次提交
    • K
      mm, fs: get rid of PAGE_CACHE_* and page_cache_{get,release} macros · 09cbfeaf
      Kirill A. Shutemov 提交于
      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
      not.
      
      The changes are pretty straight-forward:
      
       - <foo> << (PAGE_CACHE_SHIFT - PAGE_SHIFT) -> <foo>;
      
       - <foo> >> (PAGE_CACHE_SHIFT - PAGE_SHIFT) -> <foo>;
      
       - PAGE_CACHE_{SIZE,SHIFT,MASK,ALIGN} -> PAGE_{SIZE,SHIFT,MASK,ALIGN};
      
       - 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 << (PAGE_CACHE_SHIFT - PAGE_SHIFT)
      + E
      
      @@
      expression E;
      @@
      - E >> (PAGE_CACHE_SHIFT - PAGE_SHIFT)
      + E
      
      @@
      @@
      - PAGE_CACHE_SHIFT
      + PAGE_SHIFT
      
      @@
      @@
      - PAGE_CACHE_SIZE
      + PAGE_SIZE
      
      @@
      @@
      - PAGE_CACHE_MASK
      + PAGE_MASK
      
      @@
      expression E;
      @@
      - PAGE_CACHE_ALIGN(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: NKirill A. Shutemov <kirill.shutemov@linux.intel.com>
      Acked-by: NMichal Hocko <mhocko@suse.com>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      09cbfeaf
  10. 12 4月, 2015 1 次提交
  11. 07 5月, 2014 2 次提交
  12. 22 5月, 2013 1 次提交
    • L
      mm: change invalidatepage prototype to accept length · d47992f8
      Lukas Czerner 提交于
      Currently there is no way to truncate partial page where the end
      truncate point is not at the end of the page. This is because it was not
      needed and the functionality was enough for file system truncate
      operation to work properly. However more file systems now support punch
      hole feature and it can benefit from mm supporting truncating page just
      up to the certain point.
      
      Specifically, with this functionality truncate_inode_pages_range() can
      be changed so it supports truncating partial page at the end of the
      range (currently it will BUG_ON() if 'end' is not at the end of the
      page).
      
      This commit changes the invalidatepage() address space operation
      prototype to accept range to be invalidated and update all the instances
      for it.
      
      We also change the block_invalidatepage() in the same way and actually
      make a use of the new length argument implementing range invalidation.
      
      Actual file system implementations will follow except the file systems
      where the changes are really simple and should not change the behaviour
      in any way .Implementation for truncate_page_range() which will be able
      to accept page unaligned ranges will follow as well.
      Signed-off-by: NLukas Czerner <lczerner@redhat.com>
      Cc: Andrew Morton <akpm@linux-foundation.org>
      Cc: Hugh Dickins <hughd@google.com>
      d47992f8
  13. 21 3月, 2012 1 次提交
  14. 22 5月, 2010 1 次提交
    • A
      AFS: Don't put struct file on the stack · f6d335c0
      Al Viro 提交于
      Don't put struct file on the stack as it takes up quite a lot of space
      and violates lifetime rules for struct file.
      
      Rather than calling afs_readpage() indirectly from the directory routines by
      way of read_mapping_page(), split afs_readpage() to have afs_page_filler()
      that's given a key instead of a file and call read_cache_page(), specifying the
      new function directly.  Use it in afs_readpages() as well.
      
      Also make use of this in afs_mntpt_check_symlink() too for the same reason.
      Reported-by: NAl Viro <viro@zeniv.linux.org.uk>
      Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
      Signed-off-by: NDavid Howells <dhowells@redhat.com>
      f6d335c0
  15. 30 3月, 2010 1 次提交
    • T
      include cleanup: Update gfp.h and slab.h includes to prepare for breaking... · 5a0e3ad6
      Tejun Heo 提交于
      include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h
      
      percpu.h is included by sched.h and module.h and thus ends up being
      included when building most .c files.  percpu.h includes slab.h which
      in turn includes gfp.h making everything defined by the two files
      universally available and complicating inclusion dependencies.
      
      percpu.h -> slab.h dependency is about to be removed.  Prepare for
      this change by updating users of gfp and slab facilities include those
      headers directly instead of assuming availability.  As this conversion
      needs to touch large number of source files, the following script is
      used as the basis of conversion.
      
        http://userweb.kernel.org/~tj/misc/slabh-sweep.py
      
      The script does the followings.
      
      * Scan files for gfp and slab usages and update includes such that
        only the necessary includes are there.  ie. if only gfp is used,
        gfp.h, if slab is used, slab.h.
      
      * When the script inserts a new include, it looks at the include
        blocks and try to put the new include such that its order conforms
        to its surrounding.  It's put in the include block which contains
        core kernel includes, in the same order that the rest are ordered -
        alphabetical, Christmas tree, rev-Xmas-tree or at the end if there
        doesn't seem to be any matching order.
      
      * If the script can't find a place to put a new include (mostly
        because the file doesn't have fitting include block), it prints out
        an error message indicating which .h file needs to be added to the
        file.
      
      The conversion was done in the following steps.
      
      1. The initial automatic conversion of all .c files updated slightly
         over 4000 files, deleting around 700 includes and adding ~480 gfp.h
         and ~3000 slab.h inclusions.  The script emitted errors for ~400
         files.
      
      2. Each error was manually checked.  Some didn't need the inclusion,
         some needed manual addition while adding it to implementation .h or
         embedding .c file was more appropriate for others.  This step added
         inclusions to around 150 files.
      
      3. The script was run again and the output was compared to the edits
         from #2 to make sure no file was left behind.
      
      4. Several build tests were done and a couple of problems were fixed.
         e.g. lib/decompress_*.c used malloc/free() wrappers around slab
         APIs requiring slab.h to be added manually.
      
      5. The script was run on all .h files but without automatically
         editing them as sprinkling gfp.h and slab.h inclusions around .h
         files could easily lead to inclusion dependency hell.  Most gfp.h
         inclusion directives were ignored as stuff from gfp.h was usually
         wildly available and often used in preprocessor macros.  Each
         slab.h inclusion directive was examined and added manually as
         necessary.
      
      6. percpu.h was updated not to include slab.h.
      
      7. Build test were done on the following configurations and failures
         were fixed.  CONFIG_GCOV_KERNEL was turned off for all tests (as my
         distributed build env didn't work with gcov compiles) and a few
         more options had to be turned off depending on archs to make things
         build (like ipr on powerpc/64 which failed due to missing writeq).
      
         * x86 and x86_64 UP and SMP allmodconfig and a custom test config.
         * powerpc and powerpc64 SMP allmodconfig
         * sparc and sparc64 SMP allmodconfig
         * ia64 SMP allmodconfig
         * s390 SMP allmodconfig
         * alpha SMP allmodconfig
         * um on x86_64 SMP allmodconfig
      
      8. percpu.h modifications were reverted so that it could be applied as
         a separate patch and serve as bisection point.
      
      Given the fact that I had only a couple of failures from tests on step
      6, I'm fairly confident about the coverage of this conversion patch.
      If there is a breakage, it's likely to be something in one of the arch
      headers which should be easily discoverable easily on most builds of
      the specific arch.
      Signed-off-by: NTejun Heo <tj@kernel.org>
      Guess-its-ok-by: NChristoph Lameter <cl@linux-foundation.org>
      Cc: Ingo Molnar <mingo@redhat.com>
      Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
      5a0e3ad6
  16. 20 11月, 2009 1 次提交
    • D
      FS-Cache: Handle pages pending storage that get evicted under OOM conditions · 201a1542
      David Howells 提交于
      Handle netfs pages that the vmscan algorithm wants to evict from the pagecache
      under OOM conditions, but that are waiting for write to the cache.  Under these
      conditions, vmscan calls the releasepage() function of the netfs, asking if a
      page can be discarded.
      
      The problem is typified by the following trace of a stuck process:
      
      	kslowd005     D 0000000000000000     0  4253      2 0x00000080
      	 ffff88001b14f370 0000000000000046 ffff880020d0d000 0000000000000007
      	 0000000000000006 0000000000000001 ffff88001b14ffd8 ffff880020d0d2a8
      	 000000000000ddf0 00000000000118c0 00000000000118c0 ffff880020d0d2a8
      	Call Trace:
      	 [<ffffffffa00782d8>] __fscache_wait_on_page_write+0x8b/0xa7 [fscache]
      	 [<ffffffff8104c0f1>] ? autoremove_wake_function+0x0/0x34
      	 [<ffffffffa0078240>] ? __fscache_check_page_write+0x63/0x70 [fscache]
      	 [<ffffffffa00b671d>] nfs_fscache_release_page+0x4e/0xc4 [nfs]
      	 [<ffffffffa00927f0>] nfs_release_page+0x3c/0x41 [nfs]
      	 [<ffffffff810885d3>] try_to_release_page+0x32/0x3b
      	 [<ffffffff81093203>] shrink_page_list+0x316/0x4ac
      	 [<ffffffff8109372b>] shrink_inactive_list+0x392/0x67c
      	 [<ffffffff813532fa>] ? __mutex_unlock_slowpath+0x100/0x10b
      	 [<ffffffff81058df0>] ? trace_hardirqs_on_caller+0x10c/0x130
      	 [<ffffffff8135330e>] ? mutex_unlock+0x9/0xb
      	 [<ffffffff81093aa2>] shrink_list+0x8d/0x8f
      	 [<ffffffff81093d1c>] shrink_zone+0x278/0x33c
      	 [<ffffffff81052d6c>] ? ktime_get_ts+0xad/0xba
      	 [<ffffffff81094b13>] try_to_free_pages+0x22e/0x392
      	 [<ffffffff81091e24>] ? isolate_pages_global+0x0/0x212
      	 [<ffffffff8108e743>] __alloc_pages_nodemask+0x3dc/0x5cf
      	 [<ffffffff81089529>] grab_cache_page_write_begin+0x65/0xaa
      	 [<ffffffff8110f8c0>] ext3_write_begin+0x78/0x1eb
      	 [<ffffffff81089ec5>] generic_file_buffered_write+0x109/0x28c
      	 [<ffffffff8103cb69>] ? current_fs_time+0x22/0x29
      	 [<ffffffff8108a509>] __generic_file_aio_write+0x350/0x385
      	 [<ffffffff8108a588>] ? generic_file_aio_write+0x4a/0xae
      	 [<ffffffff8108a59e>] generic_file_aio_write+0x60/0xae
      	 [<ffffffff810b2e82>] do_sync_write+0xe3/0x120
      	 [<ffffffff8104c0f1>] ? autoremove_wake_function+0x0/0x34
      	 [<ffffffff810b18e1>] ? __dentry_open+0x1a5/0x2b8
      	 [<ffffffff810b1a76>] ? dentry_open+0x82/0x89
      	 [<ffffffffa00e693c>] cachefiles_write_page+0x298/0x335 [cachefiles]
      	 [<ffffffffa0077147>] fscache_write_op+0x178/0x2c2 [fscache]
      	 [<ffffffffa0075656>] fscache_op_execute+0x7a/0xd1 [fscache]
      	 [<ffffffff81082093>] slow_work_execute+0x18f/0x2d1
      	 [<ffffffff8108239a>] slow_work_thread+0x1c5/0x308
      	 [<ffffffff8104c0f1>] ? autoremove_wake_function+0x0/0x34
      	 [<ffffffff810821d5>] ? slow_work_thread+0x0/0x308
      	 [<ffffffff8104be91>] kthread+0x7a/0x82
      	 [<ffffffff8100beda>] child_rip+0xa/0x20
      	 [<ffffffff8100b87c>] ? restore_args+0x0/0x30
      	 [<ffffffff8102ef83>] ? tg_shares_up+0x171/0x227
      	 [<ffffffff8104be17>] ? kthread+0x0/0x82
      	 [<ffffffff8100bed0>] ? child_rip+0x0/0x20
      
      In the above backtrace, the following is happening:
      
       (1) A page storage operation is being executed by a slow-work thread
           (fscache_write_op()).
      
       (2) FS-Cache farms the operation out to the cache to perform
           (cachefiles_write_page()).
      
       (3) CacheFiles is then calling Ext3 to perform the actual write, using Ext3's
           standard write (do_sync_write()) under KERNEL_DS directly from the netfs
           page.
      
       (4) However, for Ext3 to perform the write, it must allocate some memory, in
           particular, it must allocate at least one page cache page into which it
           can copy the data from the netfs page.
      
       (5) Under OOM conditions, the memory allocator can't immediately come up with
           a page, so it uses vmscan to find something to discard
           (try_to_free_pages()).
      
       (6) vmscan finds a clean netfs page it might be able to discard (possibly the
           one it's trying to write out).
      
       (7) The netfs is called to throw the page away (nfs_release_page()) - but it's
           called with __GFP_WAIT, so the netfs decides to wait for the store to
           complete (__fscache_wait_on_page_write()).
      
       (8) This blocks a slow-work processing thread - possibly against itself.
      
      The system ends up stuck because it can't write out any netfs pages to the
      cache without allocating more memory.
      
      To avoid this, we make FS-Cache cancel some writes that aren't in the middle of
      actually being performed.  This means that some data won't make it into the
      cache this time.  To support this, a new FS-Cache function is added
      fscache_maybe_release_page() that replaces what the netfs releasepage()
      functions used to do with respect to the cache.
      
      The decisions fscache_maybe_release_page() makes are counted and displayed
      through /proc/fs/fscache/stats on a line labelled "VmScan".  There are four
      counters provided: "nos=N" - pages that weren't pending storage; "gon=N" -
      pages that were pending storage when we first looked, but weren't by the time
      we got the object lock; "bsy=N" - pages that we ignored as they were actively
      being written when we looked; and "can=N" - pages that we cancelled the storage
      of.
      
      What I'd really like to do is alter the behaviour of the cancellation
      heuristics, depending on how necessary it is to expel pages.  If there are
      plenty of other pages that aren't waiting to be written to the cache that
      could be ejected first, then it would be nice to hold up on immediate
      cancellation of cache writes - but I don't see a way of doing that.
      Signed-off-by: NDavid Howells <dhowells@redhat.com>
      201a1542
  17. 28 8月, 2009 1 次提交
  18. 18 4月, 2009 1 次提交
  19. 03 4月, 2009 1 次提交
  20. 17 10月, 2008 1 次提交
  21. 17 7月, 2007 1 次提交
  22. 10 7月, 2007 1 次提交
  23. 11 5月, 2007 1 次提交
  24. 10 5月, 2007 2 次提交
    • D
      AFS: implement basic file write support · 31143d5d
      David Howells 提交于
      Implement support for writing to regular AFS files, including:
      
       (1) write
      
       (2) truncate
      
       (3) fsync, fdatasync
      
       (4) chmod, chown, chgrp, utime.
      
      AFS writeback attempts to batch writes into as chunks as large as it can manage
      up to the point that it writes back 65535 pages in one chunk or it meets a
      locked page.
      
      Furthermore, if a page has been written to using a particular key, then should
      another write to that page use some other key, the first write will be flushed
      before the second is allowed to take place.  If the first write fails due to a
      security error, then the page will be scrapped and reread before the second
      write takes place.
      
      If a page is dirty and the callback on it is broken by the server, then the
      dirty data is not discarded (same behaviour as NFS).
      
      Shared-writable mappings are not supported by this patch.
      
      [akpm@linux-foundation.org: fix a bunch of warnings]
      Signed-off-by: NDavid Howells <dhowells@redhat.com>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      31143d5d
    • D
      AFS: AFS fixups · 416351f2
      David Howells 提交于
      Make some miscellaneous changes to the AFS filesystem:
      
       (1) Assert RCU barriers on module exit to make sure RCU has finished with
           callbacks in this module.
      
       (2) Correctly handle the AFS server returning a zero-length read.
      
       (3) Split out data zapping calls into one function (afs_zap_data).
      
       (4) Rename some afs_file_*() functions to afs_*() where they apply to
           non-regular files too.
      
       (5) Be consistent about the presentation of volume ID:vnode ID in debugging
           output.
      Signed-off-by: NDavid Howells <dhowells@redhat.com>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      416351f2
  25. 27 4月, 2007 3 次提交
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