1. 17 Nov, 2017 1 commit
    • David Howells's avatar
      afs: Fix file locking · 0fafdc9f
      David Howells authored
      Fix the AFS file locking whereby the use of the big kernel lock (which
      could be slept with) was replaced by a spinlock (which couldn't).  The
      problem is that the AFS code was doing stuff inside the critical section
      that might call schedule(), so this is a broken transformation.
      
      Fix this by the following means:
      
       (1) Use a state machine with a proper state that can only be changed under
           the spinlock rather than using a collection of bit flags.
      
       (2) Cache the key used for the lock and the lock type in the afs_vnode
           struct so that the manager work function doesn't have to refer to a
           file_lock struct that's been dequeued.  This makes signal handling
           safer.
      
       (4) Move the unlock from afs_do_unlk() to afs_fl_release_private() which
           means that unlock is achieved in other circumstances too.
      
       (5) Unlock the file on the server before taking the next conflicting lock.
      
      Also change:
      
       (1) Check the permits on a file before actually trying the lock.
      
       (2) fsync the file before effecting an explicit unlock operation.  We
           don't fsync if the lock is erased otherwise as we might not be in a
           context where we can actually do that.
      
      Further fixes:
      
       (1) Fixed-fileserver address rotation is made to work.  It's only used by
           the locking functions, so couldn't be tested before.
      
      Fixes: 72f98e72 ("locks: turn lock_flocks into a spinlock")
      Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
      cc: jlayton@redhat.com
      0fafdc9f
  2. 13 Nov, 2017 8 commits
    • David Howells's avatar
      afs: Overhaul volume and server record caching and fileserver rotation · d2ddc776
      David Howells authored
      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: default avatarDavid Howells <dhowells@redhat.com>
      d2ddc776
    • David Howells's avatar
      afs: Move server rotation code into its own file · 9cc6fc50
      David Howells authored
      Move server rotation code into its own file.
      Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
      9cc6fc50
    • David Howells's avatar
      afs: Add an address list concept · 8b2a464c
      David Howells authored
      Add an RCU replaceable address list structure to hold a list of server
      addresses.  The list also holds the
      
      To this end:
      
       (1) A cell's VL server address list can be loaded directly via insmod or
           echo to /proc/fs/afs/cells or dynamically from a DNS query for AFSDB
           or SRV records.
      
       (2) Anyone wanting to use a cell's VL server address must wait until the
           cell record comes online and has tried to obtain some addresses.
      
       (3) An FS server's address list, for the moment, has a single entry that
           is the key to the server list.  This will change in the future when a
           server is instead keyed on its UUID and the VL.GetAddrsU operation is
           used.
      
       (4) An 'address cursor' concept is introduced to handle iteration through
           the address list.  This is passed to the afs_make_call() as, in the
           future, stuff (such as abort code) that doesn't outlast the call will
           be returned in it.
      
      In the future, we might want to annotate the list with information about
      how each address fares.  We might then want to propagate such annotations
      over address list replacement.
      
      Whilst we're at it, we allow IPv6 addresses to be specified in
      colon-delimited lists by enclosing them in square brackets.
      Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
      8b2a464c
    • David Howells's avatar
      afs: Overhaul the callback handling · c435ee34
      David Howells authored
      Overhaul the AFS callback handling by the following means:
      
       (1) Don't give up callback promises on vnodes that we are no longer using,
           rather let them just expire on the server or let the server break
           them.  This is actually more efficient for the server as the callback
           lookup is expensive if there are lots of extant callbacks.
      
       (2) Only give up the callback promises we have from a server when the
           server record is destroyed.  Then we can just give up *all* the
           callback promises on it in one go.
      
       (3) Servers can end up being shared between cells if cells are aliased, so
           don't add all the vnodes being backed by a particular server into a
           big FID-indexed tree on that server as there may be duplicates.
      
           Instead have each volume instance (~= superblock) register an interest
           in a server as it starts to make use of it and use this to allow the
           processor for callbacks from the server to find the superblock and
           thence the inode corresponding to the FID being broken by means of
           ilookup_nowait().
      
       (4) Rather than iterating over the entire callback list when a mass-break
           comes in from the server, maintain a counter of mass-breaks in
           afs_server (cb_seq) and make afs_validate() check it against the copy
           in afs_vnode.
      
           It would be nice not to have to take a read_lock whilst doing this,
           but that's tricky without using RCU.
      
       (5) Save a ref on the fileserver we're using for a call in the afs_call
           struct so that we can access its cb_s_break during call decoding.
      
       (6) Write-lock around callback and status storage in a vnode and read-lock
           around getattr so that we don't see the status mid-update.
      
      This has the following consequences:
      
       (1) Data invalidation isn't seen until someone calls afs_validate() on a
           vnode.  Unfortunately, we need to use a key to query the server, but
           getting one from a background thread is tricky without caching loads
           of keys all over the place.
      
       (2) Mass invalidation isn't seen until someone calls afs_validate().
      
       (3) Callback breaking is going to hit the inode_hash_lock quite a bit.
           Could this be replaced with rcu_read_lock() since inodes are destroyed
           under RCU conditions.
      Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
      c435ee34
    • David Howells's avatar
      afs: Keep and pass sockaddr_rxrpc addresses rather than in_addr · 4d9df986
      David Howells authored
      Keep and pass sockaddr_rxrpc addresses around rather than keeping and
      passing in_addr addresses to allow for the use of IPv6 and non-standard
      port numbers in future.
      
      This also allows the port and service_id fields to be removed from the
      afs_call struct.
      Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
      4d9df986
    • David Howells's avatar
      afs: Update the cache index structure · ad6a942a
      David Howells authored
      Update the cache index structure in the following ways:
      
       (1) Don't use the volume name followed by the volume type as levels in the
           cache index.  Volumes can be renamed.  Use the volume ID instead.
      
       (2) Don't store the VLDB data for a volume in the tree.  If the volume
           database should be cached locally, then it should be done in a separate
           tree.
      
       (3) Expand the volume ID stored in the cache to 64 bits.
      
       (4) Expand the file/vnode ID stored in the cache to 96 bits.
      
       (5) Increment the cache structure version number to 1.
      Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
      ad6a942a
    • David Howells's avatar
      afs: Push the net ns pointer to more places · 9ed900b1
      David Howells authored
      Push the network namespace pointer to more places in AFS, including the
      afs_server structure (which doesn't hold a ref on the netns).
      
      In particular, afs_put_cell() now takes requires a net ns parameter so that
      it can safely alter the netns after decrementing the cell usage count - the
      cell will be deallocated by a background thread after being cached for a
      period, which means that it's not safe to access it after reducing its
      usage count.
      Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
      9ed900b1
    • David Howells's avatar
      afs: Lay the groundwork for supporting network namespaces · f044c884
      David Howells authored
      Lay the groundwork for supporting network namespaces (netns) to the AFS
      filesystem by moving various global features to a network-namespace struct
      (afs_net) and providing an instance of this as a temporary global variable
      that everything uses via accessor functions for the moment.
      
      The following changes have been made:
      
       (1) Store the netns in the superblock info.  This will be obtained from
           the mounter's nsproxy on a manual mount and inherited from the parent
           superblock on an automount.
      
       (2) The cell list is made per-netns.  It can be viewed through
           /proc/net/afs/cells and also be modified by writing commands to that
           file.
      
       (3) The local workstation cell is set per-ns in /proc/net/afs/rootcell.
           This is unset by default.
      
       (4) The 'rootcell' module parameter, which sets a cell and VL server list
           modifies the init net namespace, thereby allowing an AFS root fs to be
           theoretically used.
      
       (5) The volume location lists and the file lock manager are made
           per-netns.
      
       (6) The AF_RXRPC socket and associated I/O bits are made per-ns.
      
      The various workqueues remain global for the moment.
      
      Changes still to be made:
      
       (1) /proc/fs/afs/ should be moved to /proc/net/afs/ and a symlink emplaced
           from the old name.
      
       (2) A per-netns subsys needs to be registered for AFS into which it can
           store its per-netns data.
      
       (3) Rather than the AF_RXRPC socket being opened on module init, it needs
           to be opened on the creation of a superblock in that netns.
      
       (4) The socket needs to be closed when the last superblock using it is
           destroyed and all outstanding client calls on it have been completed.
           This prevents a reference loop on the namespace.
      
       (5) It is possible that several namespaces will want to use AFS, in which
           case each one will need its own UDP port.  These can either be set
           through /proc/net/afs/cm_port or the kernel can pick one at random.
           The init_ns gets 7001 by default.
      
      Other issues that need resolving:
      
       (1) The DNS keyring needs net-namespacing.
      
       (2) Where do upcalls go (eg. DNS request-key upcall)?
      
       (3) Need something like open_socket_in_file_ns() syscall so that AFS
           command line tools attempting to operate on an AFS file/volume have
           their RPC calls go to the right place.
      Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
      f044c884
  3. 20 Apr, 2017 1 commit
  4. 06 Jan, 2017 1 commit
  5. 20 Jan, 2015 1 commit
  6. 27 Sep, 2013 1 commit
    • David Howells's avatar
      FS-Cache: Provide the ability to enable/disable cookies · 94d30ae9
      David Howells authored
      Provide the ability to enable and disable fscache cookies.  A disabled cookie
      will reject or ignore further requests to:
      
      	Acquire a child cookie
      	Invalidate and update backing objects
      	Check the consistency of a backing object
      	Allocate storage for backing page
      	Read backing pages
      	Write to backing pages
      
      but still allows:
      
      	Checks/waits on the completion of already in-progress objects
      	Uncaching of pages
      	Relinquishment of cookies
      
      Two new operations are provided:
      
       (1) Disable a cookie:
      
      	void fscache_disable_cookie(struct fscache_cookie *cookie,
      				    bool invalidate);
      
           If the cookie is not already disabled, this locks the cookie against other
           dis/enablement ops, marks the cookie as being disabled, discards or
           invalidates any backing objects and waits for cessation of activity on any
           associated object.
      
           This is a wrapper around a chunk split out of fscache_relinquish_cookie(),
           but it reinitialises the cookie such that it can be reenabled.
      
           All possible failures are handled internally.  The caller should consider
           calling fscache_uncache_all_inode_pages() afterwards to make sure all page
           markings are cleared up.
      
       (2) Enable a cookie:
      
      	void fscache_enable_cookie(struct fscache_cookie *cookie,
      				   bool (*can_enable)(void *data),
      				   void *data)
      
           If the cookie is not already enabled, this locks the cookie against other
           dis/enablement ops, invokes can_enable() and, if the cookie is not an
           index cookie, will begin the procedure of acquiring backing objects.
      
           The optional can_enable() function is passed the data argument and returns
           a ruling as to whether or not enablement should actually be permitted to
           begin.
      
           All possible failures are handled internally.  The cookie will only be
           marked as enabled if provisional backing objects are allocated.
      
      A later patch will introduce these to NFS.  Cookie enablement during nfs_open()
      is then contingent on i_writecount <= 0.  can_enable() checks for a race
      between open(O_RDONLY) and open(O_WRONLY/O_RDWR).  This simplifies NFS's cookie
      handling and allows us to get rid of open(O_RDONLY) accidentally introducing
      caching to an inode that's open for writing already.
      
      One operation has its API modified:
      
       (3) Acquire a cookie.
      
      	struct fscache_cookie *fscache_acquire_cookie(
      		struct fscache_cookie *parent,
      		const struct fscache_cookie_def *def,
      		void *netfs_data,
      		bool enable);
      
           This now has an additional argument that indicates whether the requested
           cookie should be enabled by default.  It doesn't need the can_enable()
           function because the caller must prevent multiple calls for the same netfs
           object and it doesn't need to take the enablement lock because no one else
           can get at the cookie before this returns.
      
      Signed-off-by: David Howells <dhowells@redhat.com
      94d30ae9
  7. 22 Apr, 2010 1 commit
  8. 03 Apr, 2009 1 commit
  9. 21 May, 2007 1 commit
    • Alexey Dobriyan's avatar
      Detach sched.h from mm.h · e8edc6e0
      Alexey Dobriyan authored
      First thing mm.h does is including sched.h solely for can_do_mlock() inline
      function which has "current" dereference inside. By dealing with can_do_mlock()
      mm.h can be detached from sched.h which is good. See below, why.
      
      This patch
      a) removes unconditional inclusion of sched.h from mm.h
      b) makes can_do_mlock() normal function in mm/mlock.c
      c) exports can_do_mlock() to not break compilation
      d) adds sched.h inclusions back to files that were getting it indirectly.
      e) adds less bloated headers to some files (asm/signal.h, jiffies.h) that were
         getting them indirectly
      
      Net result is:
      a) mm.h users would get less code to open, read, preprocess, parse, ... if
         they don't need sched.h
      b) sched.h stops being dependency for significant number of files:
         on x86_64 allmodconfig touching sched.h results in recompile of 4083 files,
         after patch it's only 3744 (-8.3%).
      
      Cross-compile tested on
      
      	all arm defconfigs, all mips defconfigs, all powerpc defconfigs,
      	alpha alpha-up
      	arm
      	i386 i386-up i386-defconfig i386-allnoconfig
      	ia64 ia64-up
      	m68k
      	mips
      	parisc parisc-up
      	powerpc powerpc-up
      	s390 s390-up
      	sparc sparc-up
      	sparc64 sparc64-up
      	um-x86_64
      	x86_64 x86_64-up x86_64-defconfig x86_64-allnoconfig
      
      as well as my two usual configs.
      Signed-off-by: default avatarAlexey Dobriyan <adobriyan@gmail.com>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      e8edc6e0
  10. 26 Apr, 2007 4 commits
  11. 27 Sep, 2006 1 commit
  12. 16 Apr, 2005 1 commit
    • Linus Torvalds's avatar
      Linux-2.6.12-rc2 · 1da177e4
      Linus Torvalds authored
      Initial git repository build. I'm not bothering with the full history,
      even though we have it. We can create a separate "historical" git
      archive of that later if we want to, and in the meantime it's about
      3.2GB when imported into git - space that would just make the early
      git days unnecessarily complicated, when we don't have a lot of good
      infrastructure for it.
      
      Let it rip!
      1da177e4