src/afs/LINUX/osi_vm.c

   1 /*
   2  * Copyright 2000, International Business Machines Corporation and others.
   3  * All Rights Reserved.
   4  *
   5  * This software has been released under the terms of the IBM Public
   6  * License.  For details, see the LICENSE file in the top-level source
   7  * directory or online at http://www.openafs.org/dl/license10.html
   8  */
   9
  10 #include <afsconfig.h>
  11 #include "afs/param.h"
  12
  13
  14 #include "afs/sysincludes.h"    /* Standard vendor system headers */
  15 #include "afsincludes.h"        /* Afs-based standard headers */
  16 #include "afs/afs_stats.h"      /* statistics */
  17
  18 #include "osi_compat.h"
  19
  20 /* Linux VM operations
  21  *
  22  * The general model for Linux is to treat vm as a cache that's:
  23  * 1) explicitly updated by AFS when AFS writes the data to the cache file.
  24  * 2) reads go through the cache. A cache miss is satisfied by the filesystem.
  25  *
  26  * This means flushing VM is not required on this OS.
  27  */
  28
  29 /* Try to discard pages, in order to recycle a vcache entry.
  30  *
  31  * We also make some sanity checks:  ref count, open count, held locks.
  32  *
  33  * We also do some non-VM-related chores, such as releasing the cred pointer
  34  * (for AIX and Solaris) and releasing the gnode (for AIX).
  35  *
  36  * Locking:  afs_xvcache lock is held. It must not be dropped.
  37  */
  38 int
  39 osi_VM_FlushVCache(struct vcache *avc)
  40 {
  41     struct inode *ip = AFSTOV(avc);
  42
  43     if (VREFCOUNT(avc) > 1)
  44         return EBUSY;
  45
  46     if (avc->opens != 0)
  47         return EBUSY;
  48
  49     return afs_truncate(ip, 0);
  50 }
  51
  52 /* Try to invalidate pages, for "fs flush" or "fs flushv"; or
  53  * try to free pages, when deleting a file.
  54  *
  55  * Locking:  the vcache entry's lock is held.  It may be dropped and
  56  * re-obtained.
  57  *
  58  * Since we drop and re-obtain the lock, we can't guarantee that there won't
  59  * be some pages around when we return, newly created by concurrent activity.
  60  */
  61 void
  62 osi_VM_TryToSmush(struct vcache *avc, afs_ucred_t *acred, int sync)
  63 {
  64     struct inode *ip = AFSTOV(avc);
  65
  66     invalidate_remote_inode(ip);
  67 }
  68
  69 /* Flush and invalidate pages, for fsync() with INVAL flag
  70  *
  71  * Locking:  only the global lock is held.
  72  */
  73 void
  74 osi_VM_FSyncInval(struct vcache *avc)
  75 {
  76
  77 }
  78
  79 /* Try to store pages to cache, in order to store a file back to the server.
  80  *
  81  * Locking:  the vcache entry's lock is held.  It will usually be dropped and
  82  * re-obtained.
  83  */
  84 void
  85 osi_VM_StoreAllSegments(struct vcache *avc)
  86 {
  87     struct inode *ip = AFSTOV(avc);
  88
  89     if (!list_empty(&avc->pagewriters))
  90         return; /* someone already writing */
  91
  92     /* filemap_fdatasync() only exported in 2.4.5 and above */
  93     ReleaseWriteLock(&avc->lock);
  94     AFS_GUNLOCK();
  95     filemap_fdatawrite(ip->i_mapping);
  96     filemap_fdatawait(ip->i_mapping);
  97     AFS_GLOCK();
  98     ObtainWriteLock(&avc->lock, 121);
  99 }
 100
 101 /* Purge VM for a file when its callback is revoked.
 102  *
 103  * Locking:  No lock is held, not even the global lock.
 104  */
 105
 106 /* Note that for speed some of our Linux vnodeops do not initialise credp
 107  * before calling osi_FlushPages(). If credp is ever required on Linux,
 108  * then these callers should be updated.
 109  */
 110 void
 111 osi_VM_FlushPages(struct vcache *avc, afs_ucred_t *credp)
 112 {
 113     struct inode *ip = AFSTOV(avc);
 114
 115     afs_linux_lock_inode(ip);
 116     truncate_inode_pages(&ip->i_data, 0);
 117     afs_linux_unlock_inode(ip);
 118 }
 119
 120 /* Purge pages beyond end-of-file, when truncating a file.
 121  *
 122  * Locking:  no lock is held, not even the global lock.
 123  * activeV is raised.  This is supposed to block pageins, but at present
 124  * it only works on Solaris.
 125  */
 126 void
 127 osi_VM_Truncate(struct vcache *avc, int alen, afs_ucred_t *acred)
 128 {
 129     afs_truncate(AFSTOV(avc), alen);
 130 }