src/patches/suse-2.6.27.25/patches.fixes/nfs-write.c-bug-removal.patch

   1 From: ffilz@us.ibm.com
   2 Subject: Revert "NFS: Allow redirtying of a completed unstable write."
   3 Patch-mainline: REVERT patch from 2.6.27
   4 References: 442267
   5
   6 mainline commit e468bae97d243fe0e1515abaa1f7d0edf1476ad0
   7 introduces a BUG() that is apprently fairly easy to trigger.
   8 As it is just making a minor performance enhancement, it is best to
   9 revert the patch until the issue is better understood.
  10
  11 Acked-by: NeilBrown <neilb@suse.de>
  12 Signed-off-by: Neil Brown <neilb@suse.de>
  13
  14 ---
  15  fs/nfs/write.c |   65 ++++++++++++++++++++++++++++-----------------------------
  16  1 file changed, 33 insertions(+), 32 deletions(-)
  17
  18 --- a/fs/nfs/write.c
  19 +++ b/fs/nfs/write.c
  20 @@ -284,9 +284,12 @@ static int nfs_page_async_flush(struct n
  21                         return ret;
  22                 spin_lock(&inode->i_lock);
  23         }
  24 -       if (test_bit(PG_CLEAN, &req->wb_flags)) {
  25 +       if (test_bit(PG_NEED_COMMIT, &req->wb_flags)) {
  26 +               /* This request is marked for commit */
  27                 spin_unlock(&inode->i_lock);
  28 -               BUG();
  29 +               nfs_clear_page_tag_locked(req);
  30 +               nfs_pageio_complete(pgio);
  31 +               return 0;
  32         }
  33         if (nfs_set_page_writeback(page) != 0) {
  34                 spin_unlock(&inode->i_lock);
  35 @@ -460,6 +463,19 @@ nfs_mark_request_dirty(struct nfs_page *
  36         __set_page_dirty_nobuffers(req->wb_page);
  37  }
  38
  39 +/*
  40 + * Check if a request is dirty
  41 + */
  42 +static inline int
  43 +nfs_dirty_request(struct nfs_page *req)
  44 +{
  45 +       struct page *page = req->wb_page;
  46 +
  47 +       if (page == NULL || test_bit(PG_NEED_COMMIT, &req->wb_flags))
  48 +               return 0;
  49 +       return !PageWriteback(page);
  50 +}
  51 +
  52  #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
  53  /*
  54   * Add a request to the inode's commit list.
  55 @@ -472,7 +488,7 @@ nfs_mark_request_commit(struct nfs_page
  56
  57         spin_lock(&inode->i_lock);
  58         nfsi->ncommit++;
  59 -       set_bit(PG_CLEAN, &(req)->wb_flags);
  60 +       set_bit(PG_NEED_COMMIT, &(req)->wb_flags);
  61         radix_tree_tag_set(&nfsi->nfs_page_tree,
  62                         req->wb_index,
  63                         NFS_PAGE_TAG_COMMIT);
  64 @@ -483,19 +499,6 @@ nfs_mark_request_commit(struct nfs_page
  65         __mark_inode_dirty(inode, I_DIRTY_DATASYNC);
  66  }
  67
  68 -static int
  69 -nfs_clear_request_commit(struct nfs_page *req)
  70 -{
  71 -       struct page *page = req->wb_page;
  72 -
  73 -       if (test_and_clear_bit(PG_CLEAN, &(req)->wb_flags)) {
  74 -               dec_zone_page_state(page, NR_UNSTABLE_NFS);
  75 -               dec_bdi_stat(page_file_mapping(page)->backing_dev_info, BDI_RECLAIMABLE);
  76 -               return 1;
  77 -       }
  78 -       return 0;
  79 -}
  80 -
  81  static inline
  82  int nfs_write_need_commit(struct nfs_write_data *data)
  83  {
  84 @@ -505,7 +508,7 @@ int nfs_write_need_commit(struct nfs_wri
  85  static inline
  86  int nfs_reschedule_unstable_write(struct nfs_page *req)
  87  {
  88 -       if (test_and_clear_bit(PG_NEED_COMMIT, &req->wb_flags)) {
  89 +       if (test_bit(PG_NEED_COMMIT, &req->wb_flags)) {
  90                 nfs_mark_request_commit(req);
  91                 return 1;
  92         }
  93 @@ -521,12 +524,6 @@ nfs_mark_request_commit(struct nfs_page
  94  {
  95  }
  96
  97 -static inline int
  98 -nfs_clear_request_commit(struct nfs_page *req)
  99 -{
 100 -       return 0;
 101 -}
 102 -
 103  static inline
 104  int nfs_write_need_commit(struct nfs_write_data *data)
 105  {
 106 @@ -584,8 +581,11 @@ static void nfs_cancel_commit_list(struc
 107
 108         while(!list_empty(head)) {
 109                 req = nfs_list_entry(head->next);
 110 +               dec_zone_page_state(req->wb_page, NR_UNSTABLE_NFS);
 111 +               dec_bdi_stat(req->wb_page->mapping->backing_dev_info,
 112 +                               BDI_RECLAIMABLE);
 113                 nfs_list_remove_request(req);
 114 -               nfs_clear_request_commit(req);
 115 +               clear_bit(PG_NEED_COMMIT, &(req)->wb_flags);
 116                 nfs_inode_remove_request(req);
 117                 nfs_unlock_request(req);
 118         }
 119 @@ -657,7 +657,8 @@ static struct nfs_page *nfs_try_to_updat
 120                  * Note: nfs_flush_incompatible() will already
 121                  * have flushed out requests having wrong owners.
 122                  */
 123 -               if (offset > rqend
 124 +               if (!nfs_dirty_request(req)
 125 +                   || offset > rqend
 126                     || end < req->wb_offset)
 127                         goto out_flushme;
 128
 129 @@ -673,10 +674,6 @@ static struct nfs_page *nfs_try_to_updat
 130                 spin_lock(&inode->i_lock);
 131         }
 132
 133 -       if (nfs_clear_request_commit(req))
 134 -               radix_tree_tag_clear(&NFS_I(inode)->nfs_page_tree,
 135 -                               req->wb_index, NFS_PAGE_TAG_COMMIT);
 136 -
 137         /* Okay, the request matches. Update the region */
 138         if (offset < req->wb_offset) {
 139                 req->wb_offset = offset;
 140 @@ -758,7 +755,8 @@ int nfs_flush_incompatible(struct file *
 141                 req = nfs_page_find_request(page);
 142                 if (req == NULL)
 143                         return 0;
 144 -               do_flush = req->wb_page != page || req->wb_context != ctx;
 145 +               do_flush = req->wb_page != page || req->wb_context != ctx
 146 +                       || !nfs_dirty_request(req);
 147                 nfs_release_request(req);
 148                 if (!do_flush)
 149                         return 0;
 150 @@ -1363,7 +1361,10 @@ static void nfs_commit_release(void *cal
 151         while (!list_empty(&data->pages)) {
 152                 req = nfs_list_entry(data->pages.next);
 153                 nfs_list_remove_request(req);
 154 -               nfs_clear_request_commit(req);
 155 +               clear_bit(PG_NEED_COMMIT, &(req)->wb_flags);
 156 +               dec_zone_page_state(req->wb_page, NR_UNSTABLE_NFS);
 157 +               dec_bdi_stat(req->wb_page->mapping->backing_dev_info,
 158 +                               BDI_RECLAIMABLE);
 159
 160                 dprintk("NFS:       commit (%s/%lld %d@%lld)",
 161                         req->wb_context->path.dentry->d_inode->i_sb->s_id,
 162 @@ -1539,7 +1540,7 @@ int nfs_wb_page_cancel(struct inode *ino
 163                 req = nfs_page_find_request(page);
 164                 if (req == NULL)
 165                         goto out;
 166 -               if (test_bit(PG_CLEAN, &req->wb_flags)) {
 167 +               if (test_bit(PG_NEED_COMMIT, &req->wb_flags)) {
 168                         nfs_release_request(req);
 169                         break;
 170                 }