On Monday 20 Jul 2015 16:34:35 Liu Bo wrote:
> On Mon, Jun 01, 2015 at 08:52:49PM +0530, Chandan Rajendra wrote:
> > In subpagesize-blocksize scenario a page can have more than one block. So
> > in addition to PagePrivate2 flag, we would have to track the I/O status of
> > each block of a page to reliably mark the ordered extent as complete.
> > 
> > Signed-off-by: Chandan Rajendra <chan...@linux.vnet.ibm.com>
> > ---
> > 
> >  fs/btrfs/extent_io.c    |  19 +--
> >  fs/btrfs/extent_io.h    |   5 +-
> >  fs/btrfs/inode.c        | 346
> >  +++++++++++++++++++++++++++++++++++------------- fs/btrfs/ordered-data.c
> >  |  17 +++
> >  fs/btrfs/ordered-data.h |   4 +
> >  5 files changed, 287 insertions(+), 104 deletions(-)
> > 
> > diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
> > index 0110abc..55f900a 100644
> > --- a/fs/btrfs/extent_io.c
> > +++ b/fs/btrfs/extent_io.c
> > @@ -4545,11 +4545,10 @@ int extent_invalidatepage(struct extent_io_tree
> > *tree,> 
> >   * to drop the page.
> >   */
> >  
> >  static int try_release_extent_state(struct extent_map_tree *map,
> > 
> > -                               struct extent_io_tree *tree,
> > -                               struct page *page, gfp_t mask)
> > +                           struct extent_io_tree *tree,
> > +                           struct page *page, u64 start, u64 end,
> > +                           gfp_t mask)
> > 
> >  {
> > 
> > -   u64 start = page_offset(page);
> > -   u64 end = start + PAGE_CACHE_SIZE - 1;
> > 
> >     int ret = 1;
> >     
> >     if (test_range_bit(tree, start, end,
> > 
> > @@ -4583,12 +4582,12 @@ static int try_release_extent_state(struct
> > extent_map_tree *map,> 
> >   * map records are removed
> >   */
> >  
> >  int try_release_extent_mapping(struct extent_map_tree *map,
> > 
> > -                          struct extent_io_tree *tree, struct page *page,
> > -                          gfp_t mask)
> > +                   struct extent_io_tree *tree, struct page *page,
> > +                   u64 start, u64 end, gfp_t mask)
> > 
> >  {
> >  
> >     struct extent_map *em;
> > 
> > -   u64 start = page_offset(page);
> > -   u64 end = start + PAGE_CACHE_SIZE - 1;
> > +   u64 orig_start = start;
> > +   u64 orig_end = end;
> > 
> >     if ((mask & __GFP_WAIT) &&
> >     
> >         page->mapping->host->i_size > 16 * 1024 * 1024) {
> > 
> > @@ -4622,7 +4621,9 @@ int try_release_extent_mapping(struct
> > extent_map_tree *map,> 
> >                     free_extent_map(em);
> >             
> >             }
> >     
> >     }
> > 
> > -   return try_release_extent_state(map, tree, page, mask);
> > +   return try_release_extent_state(map, tree, page,
> > +                                   orig_start, orig_end,
> > +                                   mask);
> > 
> >  }
> >  
> >  /*
> > 
> > diff --git a/fs/btrfs/extent_io.h b/fs/btrfs/extent_io.h
> > index 8fe5ac3..c629e53 100644
> > --- a/fs/btrfs/extent_io.h
> > +++ b/fs/btrfs/extent_io.h
> > @@ -217,8 +217,9 @@ typedef struct extent_map *(get_extent_t)(struct inode
> > *inode,> 
> >  void extent_io_tree_init(struct extent_io_tree *tree,
> >  
> >                      struct address_space *mapping);
> >  
> >  int try_release_extent_mapping(struct extent_map_tree *map,
> > 
> > -                          struct extent_io_tree *tree, struct page *page,
> > -                          gfp_t mask);
> > +                   struct extent_io_tree *tree, struct page *page,
> > +                   u64 start, u64 end,
> > +                   gfp_t mask);
> > 
> >  int try_release_extent_buffer(struct page *page);
> >  int lock_extent(struct extent_io_tree *tree, u64 start, u64 end);
> >  int lock_extent_bits(struct extent_io_tree *tree, u64 start, u64 end,
> > 
> > diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
> > index bff60c6..bfffc62 100644
> > --- a/fs/btrfs/inode.c
> > +++ b/fs/btrfs/inode.c
> > @@ -2990,56 +2990,115 @@ static void finish_ordered_fn(struct btrfs_work
> > *work)> 
> >     btrfs_finish_ordered_io(ordered_extent);
> >  
> >  }
> > 
> > -static int btrfs_writepage_end_io_hook(struct page *page, u64 start, u64
> > end, -                              struct extent_state *state, int 
uptodate)
> > +static void mark_blks_io_complete(struct btrfs_ordered_extent *ordered,
> > +                           u64 blk, u64 nr_blks, int uptodate)
> > 
> >  {
> > 
> > -   struct inode *inode = page->mapping->host;
> > +   struct inode *inode = ordered->inode;
> > 
> >     struct btrfs_root *root = BTRFS_I(inode)->root;
> > 
> > -   struct btrfs_ordered_extent *ordered_extent = NULL;
> > 
> >     struct btrfs_workqueue *wq;
> >     btrfs_work_func_t func;
> > 
> > -   u64 ordered_start, ordered_end;
> > 
> >     int done;
> > 
> > -   trace_btrfs_writepage_end_io_hook(page, start, end, uptodate);
> > +   while (nr_blks--) {
> > +           if (test_and_set_bit(blk, ordered->blocks_done)) {
> > +                   blk++;
> > +                   continue;
> > +           }
> > 
> > -   ClearPagePrivate2(page);
> > -loop:
> > -   ordered_extent = btrfs_lookup_ordered_range(inode, start,
> > -                                           end - start + 1);
> > -   if (!ordered_extent)
> > -           goto out;
> > +           done = btrfs_dec_test_ordered_pending(inode, &ordered,
> > +                                           ordered->file_offset
> > +                                           + (blk << inode->i_sb-
>s_blocksize_bits),
> > +                                           root->sectorsize,
> > +                                           uptodate);
> > +           if (done) {
> > +                   if (btrfs_is_free_space_inode(inode)) {
> > +                           wq = root->fs_info->endio_freespace_worker;
> > +                           func = btrfs_freespace_write_helper;
> > +                   } else {
> > +                           wq = root->fs_info->endio_write_workers;
> > +                           func = btrfs_endio_write_helper;
> > +                   }
> > 
> > -   ordered_start = max_t(u64, start, ordered_extent->file_offset);
> > -   ordered_end = min_t(u64, end,
> > -                   ordered_extent->file_offset + ordered_extent->len - 
1);
> > -
> > -   done = btrfs_dec_test_ordered_pending(inode, &ordered_extent,
> > -                                   ordered_start,
> > -                                   ordered_end - ordered_start + 1,
> > -                                   uptodate);
> > -   if (done) {
> > -           if (btrfs_is_free_space_inode(inode)) {
> > -                   wq = root->fs_info->endio_freespace_worker;
> > -                   func = btrfs_freespace_write_helper;
> > -           } else {
> > -                   wq = root->fs_info->endio_write_workers;
> > -                   func = btrfs_endio_write_helper;
> > +                   btrfs_init_work(&ordered->work, func,
> > +                                   finish_ordered_fn, NULL, NULL);
> > +                   btrfs_queue_work(wq, &ordered->work);
> > 
> >             }
> > 
> > -           btrfs_init_work(&ordered_extent->work, func,
> > -                           finish_ordered_fn, NULL, NULL);
> > -           btrfs_queue_work(wq, &ordered_extent->work);
> > +           blk++;
> > 
> >     }
> > 
> > +}
> > 
> > -   btrfs_put_ordered_extent(ordered_extent);
> > +int btrfs_writepage_end_io_hook(struct page *page, u64 start, u64 end,
> > +                           struct extent_state *state, int uptodate)
> > +{
> > +   struct inode *inode = page->mapping->host;
> > +   struct btrfs_root *root = BTRFS_I(inode)->root;
> > +   struct btrfs_ordered_extent *ordered_extent = NULL;
> > +   u64 blk, nr_blks;
> > +   int clear;
> > 
> > -   start = ordered_end + 1;
> > +   trace_btrfs_writepage_end_io_hook(page, start, end, uptodate);
> > 
> > -   if (start < end)
> > -           goto loop;
> > +   while (start < end) {
> > +           ordered_extent = btrfs_lookup_ordered_extent(inode, start);
> > +           if (!ordered_extent) {
> > +                   start += root->sectorsize;
> > +                   continue;
> > +           }
> > +
> > +           blk = (start - ordered_extent->file_offset)
> > +                   >> inode->i_sb->s_blocksize_bits;
> > +
> > +           nr_blks = (min(end, ordered_extent->file_offset + 
ordered_extent->len -
> > 1) +                        + 1 - start) >> inode->i_sb->s_blocksize_bits;
> > +
> > +           BUG_ON(!nr_blks);
> > +
> > +           mark_blks_io_complete(ordered_extent, blk, nr_blks, uptodate);
> 
> Range [start, end] is surely contiguous, so why are we processing blocks
> one by one in mark_blks_io_complete()?
>
Liu, Thanks for pointing it out. We can actually get rid of the loop in
mark_blks_io_complete() and set the bits (corresponding to the blocks in the
range [start, end]) at btrfs_ordered_extent->blocks_done using bitmap_set().

> Same question for invalidatepage().
Unfortunately for btrfs_invalidatepage(), we need to loop across the blocks
sequentially. Consider the following file operations,

1. Write blocks [0, 7] to a file. Assume all the 8 blocks are part of the same
   ordered extent.
2. Punch a hole starting at block 4 and spanning two blocks in length.
   Here btrfs_invalidatepage() gets invoked and hence
   btrfs_ordered_extent->bytes_left gets decremented by (2 * sectorsize).
3. Punch a hole starting at block 3 and spanning two blocks in length. Again,
   btrfs_invalidatepage() gets invoked and hence
   btrfs_ordered_extent->bytes_left gets decremented by (2 * sectorsize). This
   isn't corrent since block 4 was already accounted for in step 2.

Hence we will have to check each block's completion status before invoking
btrfs_dec_test_ordered_pending().

> 
> Thanks,
> 
> -liubo
> 
> > +
> > +           start = ordered_extent->file_offset + ordered_extent->len;
> > +
> > +           btrfs_put_ordered_extent(ordered_extent);
> > +   }
> > +
> > +   start = page_offset(page);
> > +   end = start + PAGE_CACHE_SIZE - 1;
> > +   clear = 1;
> > +
> > +   while (start < end) {
> > +           ordered_extent = btrfs_lookup_ordered_extent(inode, start);
> > +           if (!ordered_extent) {
> > +                   start += root->sectorsize;
> > +                   continue;
> > +           }
> > +
> > +           blk = (start - ordered_extent->file_offset)
> > +                   >> inode->i_sb->s_blocksize_bits;
> > +           nr_blks = (min(end, ordered_extent->file_offset + 
ordered_extent->len -
> > 1) +                        + 1  - start) >> inode->i_sb-
>s_blocksize_bits;
> > +
> > +           BUG_ON(!nr_blks);
> > +
> > +           while (nr_blks--) {
> > +                   if (!test_bit(blk++, ordered_extent->blocks_done)) {
> > +                           clear = 0;
> > +                           break;
> > +                   }
> > +           }
> > +
> > +           if (!clear) {
> > +                   btrfs_put_ordered_extent(ordered_extent);
> > +                   break;
> > +           }
> > +
> > +           start += ordered_extent->len;
> > +
> > +           btrfs_put_ordered_extent(ordered_extent);
> > +   }
> > +
> > +   if (clear)
> > +           ClearPagePrivate2(page);
> > 
> > -out:
> >     return 0;
> >  
> >  }
> > 
> > @@ -8472,7 +8531,9 @@ btrfs_readpages(struct file *file, struct
> > address_space *mapping,> 
> >     return extent_readpages(tree, mapping, pages, nr_pages,
> >     
> >                             btrfs_get_extent);
> >  
> >  }
> > 
> > -static int __btrfs_releasepage(struct page *page, gfp_t gfp_flags)
> > +
> > +static int __btrfs_releasepage(struct page *page, u64 start, u64 end,
> > +                   gfp_t gfp_flags)
> > 
> >  {
> >  
> >     struct extent_io_tree *tree;
> >     struct extent_map_tree *map;
> > 
> > @@ -8480,31 +8541,149 @@ static int __btrfs_releasepage(struct page *page,
> > gfp_t gfp_flags)> 
> >     tree = &BTRFS_I(page->mapping->host)->io_tree;
> >     map = &BTRFS_I(page->mapping->host)->extent_tree;
> > 
> > -   ret = try_release_extent_mapping(map, tree, page, gfp_flags);
> > -   if (ret == 1)
> > +
> > +   ret = try_release_extent_mapping(map, tree, page, start, end,
> > +                                   gfp_flags);
> > +   if ((ret == 1) && ((end - start + 1) == PAGE_CACHE_SIZE)) {
> > 
> >             clear_page_extent_mapped(page);
> > 
> > +   } else {
> > +           ret = 0;
> > +   }
> > 
> >     return ret;
> >  
> >  }
> >  
> >  static int btrfs_releasepage(struct page *page, gfp_t gfp_flags)
> >  {
> > 
> > +   u64 start = page_offset(page);
> > +   u64 end = start + PAGE_CACHE_SIZE - 1;
> > +
> > 
> >     if (PageWriteback(page) || PageDirty(page))
> >     
> >             return 0;
> > 
> > -   return __btrfs_releasepage(page, gfp_flags & GFP_NOFS);
> > +
> > +   return __btrfs_releasepage(page, start, end, gfp_flags & GFP_NOFS);
> > +}
> > +
> > +static void invalidate_ordered_extent_blocks(struct inode *inode,
> > +                                   struct btrfs_ordered_extent *ordered,
> > +                                   u64 locked_start, u64 locked_end,
> > +                                   u64 cur,
> > +                                   int inode_evicting)
> > +{
> > +   struct btrfs_root *root = BTRFS_I(inode)->root;
> > +   struct btrfs_ordered_inode_tree *ordered_tree;
> > +   struct extent_io_tree *tree;
> > +   u64 blk, blk_done, nr_blks;
> > +   u64 end;
> > +   u64 new_len;
> > +
> > +   tree = &BTRFS_I(inode)->io_tree;
> > +
> > +   end = min(locked_end, ordered->file_offset + ordered->len - 1);
> > +
> > +   if (!inode_evicting) {
> > +           clear_extent_bit(tree, cur, end,
> > +                           EXTENT_DIRTY | EXTENT_DELALLOC |
> > +                           EXTENT_DO_ACCOUNTING |
> > +                           EXTENT_DEFRAG, 1, 0, NULL,
> > +                           GFP_NOFS);
> > +           unlock_extent(tree, locked_start, locked_end);
> > +   }
> > +
> > +
> > +   ordered_tree = &BTRFS_I(inode)->ordered_tree;
> > +   spin_lock_irq(&ordered_tree->lock);
> > +   set_bit(BTRFS_ORDERED_TRUNCATED, &ordered->flags);
> > +   new_len = cur - ordered->file_offset;
> > +   if (new_len < ordered->truncated_len)
> > +           ordered->truncated_len = new_len;
> > +
> > +   blk = (cur - ordered->file_offset) >> inode->i_sb->s_blocksize_bits;
> > +   nr_blks = (end + 1 - cur) >> inode->i_sb->s_blocksize_bits;
> > +
> > +   while (nr_blks--) {
> > +           blk_done = !test_and_set_bit(blk, ordered->blocks_done);
> > +           if (blk_done) {
> > +                   spin_unlock_irq(&ordered_tree->lock);
> > +                   if (btrfs_dec_test_ordered_pending(inode, &ordered,
> > +                                                           ordered-
>file_offset + (blk << inode->i_sb->s_blocksize_bits),
> > +                                                           root-
>sectorsize,
> > +                                                           1))
> > +                           btrfs_finish_ordered_io(ordered);
> > +
> > +                   spin_lock_irq(&ordered_tree->lock);
> > +           }
> > +           blk++;
> > +   }
> > +
> > +   spin_unlock_irq(&ordered_tree->lock);
> > +
> > +   if (!inode_evicting)
> > +           lock_extent_bits(tree, locked_start, locked_end, 0, NULL);
> > +}
> > +
> > +static int page_blocks_written(struct page *page)
> > +{
> > +   struct btrfs_ordered_extent *ordered;
> > +   struct btrfs_root *root;
> > +   struct inode *inode;
> > +   unsigned long outstanding_blk;
> > +   u64 page_start, page_end;
> > +   u64 blk, last_blk, nr_blks;
> > +   u64 cur;
> > +   u64 len;
> > +
> > +   inode = page->mapping->host;
> > +   root = BTRFS_I(inode)->root;
> > +
> > +   page_start = page_offset(page);
> > +   page_end = page_start + PAGE_CACHE_SIZE - 1;
> > +
> > +   cur = page_start;
> > +   while (cur < page_end) {
> > +           ordered = btrfs_lookup_ordered_extent(inode, cur);
> > +           if (!ordered) {
> > +                   cur += root->sectorsize;
> > +                   continue;
> > +           }
> > +
> > +           blk = (cur - ordered->file_offset)
> > +                   >> inode->i_sb->s_blocksize_bits;
> > +           len = min(page_end, ordered->file_offset + ordered->len - 1)
> > +                   - cur + 1;
> > +           nr_blks = len >> inode->i_sb->s_blocksize_bits;
> > +
> > +           last_blk = blk + nr_blks - 1;
> > +
> > +           outstanding_blk = find_next_zero_bit(ordered->blocks_done,
> > +                                           ordered->len >> inode->i_sb-
>s_blocksize_bits,
> > +                                           blk);
> > +           if (outstanding_blk <= last_blk) {
> > +                   btrfs_put_ordered_extent(ordered);
> > +                   return 0;
> > +           }
> > +
> > +           btrfs_put_ordered_extent(ordered);
> > +           cur += len;
> > +   }
> > +
> > +   return 1;
> > 
> >  }
> >  
> >  static void btrfs_invalidatepage(struct page *page, unsigned int offset,
> > 
> > -                            unsigned int length)
> > +                           unsigned int length)
> > 
> >  {
> >  
> >     struct inode *inode = page->mapping->host;
> > 
> > +   struct btrfs_root *root = BTRFS_I(inode)->root;
> > 
> >     struct extent_io_tree *tree;
> >     struct btrfs_ordered_extent *ordered;
> > 
> > -   struct extent_state *cached_state = NULL;
> > -   u64 page_start = page_offset(page);
> > -   u64 page_end = page_start + PAGE_CACHE_SIZE - 1;
> > +   u64 start, end, cur;
> > +   u64 page_start, page_end;
> > 
> >     int inode_evicting = inode->i_state & I_FREEING;
> > 
> > +   page_start = page_offset(page);
> > +   page_end = page_start + PAGE_CACHE_SIZE - 1;
> > +
> > 
> >     /*
> >     
> >      * we have the page locked, so new writeback can't start,
> >      * and the dirty bit won't be cleared while we are here.
> > 
> > @@ -8515,73 +8694,54 @@ static void btrfs_invalidatepage(struct page
> > *page, unsigned int offset,> 
> >     wait_on_page_writeback(page);
> >     
> >     tree = &BTRFS_I(inode)->io_tree;
> > 
> > -   if (offset) {
> > +
> > +   start = round_up(offset, root->sectorsize);
> > +   end = round_down(offset + length, root->sectorsize) - 1;
> > +   if (end - start + 1 < root->sectorsize) {
> > 
> >             btrfs_releasepage(page, GFP_NOFS);
> >             return;
> >     
> >     }
> > 
> > +   start = round_up(page_start + offset, root->sectorsize);
> > +   end = round_down(page_start + offset + length,
> > +                   root->sectorsize) - 1;
> > +
> > 
> >     if (!inode_evicting)
> > 
> > -           lock_extent_bits(tree, page_start, page_end, 0, 
&cached_state);
> > -   ordered = btrfs_lookup_ordered_range(inode, page_start,
> > PAGE_CACHE_SIZE);
> > -   if (ordered) {
> > -           /*
> > -            * IO on this page will never be started, so we need
> > -            * to account for any ordered extents now
> > -            */
> > -           if (!inode_evicting)
> > -                   clear_extent_bit(tree, page_start, page_end,
> > -                                    EXTENT_DIRTY | EXTENT_DELALLOC |
> > -                                    EXTENT_LOCKED | EXTENT_DO_ACCOUNTING 
|
> > -                                    EXTENT_DEFRAG, 1, 0, &cached_state,
> > -                                    GFP_NOFS);
> > -           /*
> > -            * whoever cleared the private bit is responsible
> > -            * for the finish_ordered_io
> > -            */
> > -           if (TestClearPagePrivate2(page)) {
> > -                   struct btrfs_ordered_inode_tree *tree;
> > -                   u64 new_len;
> > +           lock_extent_bits(tree, start, end, 0, NULL);
> > 
> > -                   tree = &BTRFS_I(inode)->ordered_tree;
> > +   cur = start;
> > +   while (cur < end) {
> > +           ordered = btrfs_lookup_ordered_extent(inode, cur);
> > +           if (!ordered) {
> > +                   cur += root->sectorsize;
> > +                   continue;
> > +           }
> > 
> > -                   spin_lock_irq(&tree->lock);
> > -                   set_bit(BTRFS_ORDERED_TRUNCATED, &ordered->flags);
> > -                   new_len = page_start - ordered->file_offset;
> > -                   if (new_len < ordered->truncated_len)
> > -                           ordered->truncated_len = new_len;
> > -                   spin_unlock_irq(&tree->lock);
> > +           invalidate_ordered_extent_blocks(inode, ordered,
> > +                                           start, end, cur,
> > +                                           inode_evicting);
> > 
> > -                   if (btrfs_dec_test_ordered_pending(inode, &ordered,
> > -                                                      page_start,
> > -                                                      PAGE_CACHE_SIZE, 
1))
> > -                           btrfs_finish_ordered_io(ordered);
> > -           }
> > +           cur = min(end + 1, ordered->file_offset + ordered->len);
> > 
> >             btrfs_put_ordered_extent(ordered);
> > 
> > -           if (!inode_evicting) {
> > -                   cached_state = NULL;
> > -                   lock_extent_bits(tree, page_start, page_end, 0,
> > -                                    &cached_state);
> > -           }
> > 
> >     }
> > 
> > -   if (!inode_evicting) {
> > -           clear_extent_bit(tree, page_start, page_end,
> > -                            EXTENT_LOCKED | EXTENT_DIRTY |
> > -                            EXTENT_DELALLOC | EXTENT_DO_ACCOUNTING |
> > -                            EXTENT_DEFRAG, 1, 1,
> > -                            &cached_state, GFP_NOFS);
> > +   if (page_blocks_written(page))
> > +           ClearPagePrivate2(page);
> > 
> > -           __btrfs_releasepage(page, GFP_NOFS);
> > +   if (!inode_evicting) {
> > +           clear_extent_bit(tree, start, end,
> > +                           EXTENT_LOCKED | EXTENT_DIRTY |
> > +                           EXTENT_DELALLOC | EXTENT_DO_ACCOUNTING |
> > +                           EXTENT_DEFRAG, 1, 1, NULL, GFP_NOFS);
> > 
> >     }
> > 
> > -   ClearPageChecked(page);
> > -   if (PagePrivate(page)) {
> > -           ClearPagePrivate(page);
> > -           set_page_private(page, 0);
> > -           page_cache_release(page);
> > +   if (!offset && length == PAGE_CACHE_SIZE) {
> > +           WARN_ON(!__btrfs_releasepage(page, start, end, GFP_NOFS));
> > +           ClearPageChecked(page);
> > 
> >     }
> >  
> >  }
> > 
> > +
> > 
> >  /*
> >  
> >   * btrfs_page_mkwrite() is not allowed to change the file size as it gets
> >   * called from a page fault handler when a page is first dirtied. Hence
> >   we must> 
> > diff --git a/fs/btrfs/ordered-data.c b/fs/btrfs/ordered-data.c
> > index 157cc54..8e614ca 100644
> > --- a/fs/btrfs/ordered-data.c
> > +++ b/fs/btrfs/ordered-data.c
> > @@ -189,12 +189,25 @@ static int __btrfs_add_ordered_extent(struct inode
> > *inode, u64 file_offset,> 
> >     struct btrfs_ordered_inode_tree *tree;
> >     struct rb_node *node;
> >     struct btrfs_ordered_extent *entry;
> > 
> > +   u64 nr_longs;
> > 
> >     tree = &BTRFS_I(inode)->ordered_tree;
> >     entry = kmem_cache_zalloc(btrfs_ordered_extent_cache, GFP_NOFS);
> >     if (!entry)
> >     
> >             return -ENOMEM;
> > 
> > +   nr_longs = BITS_TO_LONGS(len >> inode->i_sb->s_blocksize_bits);
> > +   if (nr_longs == 1) {
> > +           entry->blocks_done = &entry->blocks_bitmap;
> > +   } else {
> > +           entry->blocks_done = kzalloc(nr_longs * sizeof(unsigned long),
> > +                                   GFP_NOFS);
> > +           if (!entry->blocks_done) {
> > +                   kmem_cache_free(btrfs_ordered_extent_cache, entry);
> > +                   return -ENOMEM;
> > +           }
> > +   }
> > +
> > 
> >     entry->file_offset = file_offset;
> >     entry->start = start;
> >     entry->len = len;
> > 
> > @@ -553,6 +566,10 @@ void btrfs_put_ordered_extent(struct
> > btrfs_ordered_extent *entry)> 
> >                     list_del(&sum->list);
> >                     kfree(sum);
> >             
> >             }
> > 
> > +
> > +           if (entry->blocks_done != &entry->blocks_bitmap)
> > +                   kfree(entry->blocks_done);
> > +
> > 
> >             kmem_cache_free(btrfs_ordered_extent_cache, entry);
> >     
> >     }
> >  
> >  }
> > 
> > diff --git a/fs/btrfs/ordered-data.h b/fs/btrfs/ordered-data.h
> > index e96cd4c..4b3356a 100644
> > --- a/fs/btrfs/ordered-data.h
> > +++ b/fs/btrfs/ordered-data.h
> > @@ -140,6 +140,10 @@ struct btrfs_ordered_extent {
> > 
> >     struct completion completion;
> >     struct btrfs_work flush_work;
> >     struct list_head work_list;
> > 
> > +
> > +   /* bitmap to track the blocks that have been written to disk */
> > +   unsigned long *blocks_done;
> > +   unsigned long blocks_bitmap;
> > 
> >  };
> >  
> >  /*

-- 
chandan

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