src/patches/suse-2.6.27.31/patches.suse/SoN-29-nfs-swapper.patch

   1 From: Peter Zijlstra <a.p.zijlstra@chello.nl>
   2 Subject: nfs: disable data cache revalidation for swapfiles
   3 Patch-mainline: No
   4 References: FATE#303834
   5
   6 Do as Trond suggested:
   7   http://lkml.org/lkml/2006/8/25/348
   8
   9 Disable NFS data cache revalidation on swap files since it doesn't really
  10 make sense to have other clients change the file while you are using it.
  11
  12 Thereby we can stop setting PG_private on swap pages, since there ought to
  13 be no further races with invalidate_inode_pages2() to deal with.
  14
  15 And since we cannot set PG_private we cannot use page->private (which is
  16 already used by PG_swapcache pages anyway) to store the nfs_page. Thus
  17 augment the new nfs_page_find_request logic.
  18
  19 Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
  20 Acked-by: Neil Brown <neilb@suse.de>
  21 Acked-by: Suresh Jayaraman <sjayaraman@suse.de>
  22
  23 ---
  24  fs/nfs/inode.c |    6 ++++
  25  fs/nfs/write.c |   71 ++++++++++++++++++++++++++++++++++++++++++++++-----------
  26  2 files changed, 64 insertions(+), 13 deletions(-)
  27
  28 --- a/fs/nfs/inode.c
  29 +++ b/fs/nfs/inode.c
  30 @@ -824,6 +824,12 @@ int nfs_revalidate_mapping_nolock(struct
  31         struct nfs_inode *nfsi = NFS_I(inode);
  32         int ret = 0;
  33
  34 +       /*
  35 +        * swapfiles are not supposed to be shared.
  36 +        */
  37 +       if (IS_SWAPFILE(inode))
  38 +               goto out;
  39 +
  40         if ((nfsi->cache_validity & NFS_INO_REVAL_PAGECACHE)
  41                         || nfs_attribute_timeout(inode) || NFS_STALE(inode)) {
  42                 ret = __nfs_revalidate_inode(NFS_SERVER(inode), inode);
  43 --- a/fs/nfs/write.c
  44 +++ b/fs/nfs/write.c
  45 @@ -104,25 +104,62 @@ static void nfs_context_set_write_error(
  46         set_bit(NFS_CONTEXT_ERROR_WRITE, &ctx->flags);
  47  }
  48
  49 -static struct nfs_page *nfs_page_find_request_locked(struct page *page)
  50 +static struct nfs_page *
  51 +__nfs_page_find_request_locked(struct nfs_inode *nfsi, struct page *page, int get)
  52  {
  53         struct nfs_page *req = NULL;
  54
  55 -       if (PagePrivate(page)) {
  56 +       if (PagePrivate(page))
  57                 req = (struct nfs_page *)page_private(page);
  58 -               if (req != NULL)
  59 -                       kref_get(&req->wb_kref);
  60 -       }
  61 +       else if (unlikely(PageSwapCache(page)))
  62 +               req = radix_tree_lookup(&nfsi->nfs_page_tree, page_file_index(page));
  63 +
  64 +       if (get && req)
  65 +               kref_get(&req->wb_kref);
  66 +
  67         return req;
  68  }
  69
  70 +static inline struct nfs_page *
  71 +nfs_page_find_request_locked(struct nfs_inode *nfsi, struct page *page)
  72 +{
  73 +       return __nfs_page_find_request_locked(nfsi, page, 1);
  74 +}
  75 +
  76 +static int __nfs_page_has_request(struct page *page)
  77 +{
  78 +       struct inode *inode = page_file_mapping(page)->host;
  79 +       struct nfs_page *req = NULL;
  80 +
  81 +       spin_lock(&inode->i_lock);
  82 +       req = __nfs_page_find_request_locked(NFS_I(inode), page, 0);
  83 +       spin_unlock(&inode->i_lock);
  84 +
  85 +       /*
  86 +        * hole here plugged by the caller holding onto PG_locked
  87 +        */
  88 +
  89 +       return req != NULL;
  90 +}
  91 +
  92 +static inline int nfs_page_has_request(struct page *page)
  93 +{
  94 +       if (PagePrivate(page))
  95 +               return 1;
  96 +
  97 +       if (unlikely(PageSwapCache(page)))
  98 +               return __nfs_page_has_request(page);
  99 +
 100 +       return 0;
 101 +}
 102 +
 103  static struct nfs_page *nfs_page_find_request(struct page *page)
 104  {
 105         struct inode *inode = page_file_mapping(page)->host;
 106         struct nfs_page *req = NULL;
 107
 108         spin_lock(&inode->i_lock);
 109 -       req = nfs_page_find_request_locked(page);
 110 +       req = nfs_page_find_request_locked(NFS_I(inode), page);
 111         spin_unlock(&inode->i_lock);
 112         return req;
 113  }
 114 @@ -226,7 +263,7 @@ static int nfs_page_async_flush(struct n
 115
 116         spin_lock(&inode->i_lock);
 117         for(;;) {
 118 -               req = nfs_page_find_request_locked(page);
 119 +               req = nfs_page_find_request_locked(NFS_I(inode), page);
 120                 if (req == NULL) {
 121                         spin_unlock(&inode->i_lock);
 122                         return 0;
 123 @@ -349,8 +386,14 @@ static int nfs_inode_add_request(struct
 124                 if (nfs_have_delegation(inode, FMODE_WRITE))
 125                         nfsi->change_attr++;
 126         }
 127 -       SetPagePrivate(req->wb_page);
 128 -       set_page_private(req->wb_page, (unsigned long)req);
 129 +       /*
 130 +        * Swap-space should not get truncated. Hence no need to plug the race
 131 +        * with invalidate/truncate.
 132 +        */
 133 +       if (likely(!PageSwapCache(req->wb_page))) {
 134 +               SetPagePrivate(req->wb_page);
 135 +               set_page_private(req->wb_page, (unsigned long)req);
 136 +       }
 137         nfsi->npages++;
 138         kref_get(&req->wb_kref);
 139         radix_tree_tag_set(&nfsi->nfs_page_tree, req->wb_index,
 140 @@ -372,8 +415,10 @@ static void nfs_inode_remove_request(str
 141         BUG_ON (!NFS_WBACK_BUSY(req));
 142
 143         spin_lock(&inode->i_lock);
 144 -       set_page_private(req->wb_page, 0);
 145 -       ClearPagePrivate(req->wb_page);
 146 +       if (likely(!PageSwapCache(req->wb_page))) {
 147 +               set_page_private(req->wb_page, 0);
 148 +               ClearPagePrivate(req->wb_page);
 149 +       }
 150         radix_tree_delete(&nfsi->nfs_page_tree, req->wb_index);
 151         nfsi->npages--;
 152         if (!nfsi->npages) {
 153 @@ -577,7 +622,7 @@ static struct nfs_page *nfs_try_to_updat
 154         spin_lock(&inode->i_lock);
 155
 156         for (;;) {
 157 -               req = nfs_page_find_request_locked(page);
 158 +               req = nfs_page_find_request_locked(NFS_I(inode), page);
 159                 if (req == NULL)
 160                         goto out_unlock;
 161
 162 @@ -1488,7 +1533,7 @@ int nfs_wb_page_cancel(struct inode *ino
 163                 if (ret < 0)
 164                         goto out;
 165         }
 166 -       if (!PagePrivate(page))
 167 +       if (!nfs_page_has_request(page))
 168                 return 0;
 169         ret = nfs_sync_mapping_wait(page_file_mapping(page), &wbc, FLUSH_INVALIDATE);
 170  out: