On Fri, Aug 31, 2012 at 06:21:38PM -0400, Lukas Czerner wrote:
> mm now supports invalidatepage_range address space operation and there
> are two file system using jbd2 also implementing punch hole feature
> which can benefit from this. We need to implement the same thing for
> jbd2 layer in order to allow those file system take benefit of this
> functionality.
>
> With new function jbd2_journal_invalidatepage_range() we can now specify
> length to invalidate, rather than assuming invalidate to the end of the
> page.
>
> Signed-off-by: Lukas Czerner <lczerner@xxxxxxxxxx>
> ---
> fs/jbd2/journal.c | 1 +
> fs/jbd2/transaction.c | 19 +++++++++++++++++--
> include/linux/jbd2.h | 2 ++
> 3 files changed, 20 insertions(+), 2 deletions(-)
>
> diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c
> index e149b99..e4618e9 100644
> --- a/fs/jbd2/journal.c
> +++ b/fs/jbd2/journal.c
> @@ -86,6 +86,7 @@ EXPORT_SYMBOL(jbd2_journal_force_commit_nested);
> EXPORT_SYMBOL(jbd2_journal_wipe);
> EXPORT_SYMBOL(jbd2_journal_blocks_per_page);
> EXPORT_SYMBOL(jbd2_journal_invalidatepage);
> +EXPORT_SYMBOL(jbd2_journal_invalidatepage_range);
> EXPORT_SYMBOL(jbd2_journal_try_to_free_buffers);
> EXPORT_SYMBOL(jbd2_journal_force_commit);
> EXPORT_SYMBOL(jbd2_journal_file_inode);
> diff --git a/fs/jbd2/transaction.c b/fs/jbd2/transaction.c
> index fb1ab953..65c1374 100644
> --- a/fs/jbd2/transaction.c
> +++ b/fs/jbd2/transaction.c
> @@ -1993,10 +1993,20 @@ zap_buffer_unlocked:
> *
> */
> void jbd2_journal_invalidatepage(journal_t *journal,
> - struct page *page,
> - unsigned long offset)
> + struct page *page,
> + unsigned long offset)
> +{
> + jbd2_journal_invalidatepage_range(journal, page, offset,
> + PAGE_CACHE_SIZE - offset);
> +}
> +
> +void jbd2_journal_invalidatepage_range(journal_t *journal,
> + struct page *page,
> + unsigned int offset,
> + unsigned int length)
> {
> struct buffer_head *head, *bh, *next;
> + unsigned int stop = offset + length;
> unsigned int curr_off = 0;
> int may_free = 1;
>
> @@ -2005,6 +2015,8 @@ void jbd2_journal_invalidatepage(journal_t *journal,
> if (!page_has_buffers(page))
> return;
>
> + BUG_ON(stop > PAGE_CACHE_SIZE || stop < length);
This misses e.g. length == (unsigned int)(-1), offset = 1. Could make
it obvious with:
BUG_ON(offset > PAGE_CACHE_SIZE || length > PAGE_CACHE_SIZE);
BUG_ON(stop > PAGE_CACHE_SIZE);
Or is that overkill?
--b.
> +
> /* We will potentially be playing with lists other than just the
> * data lists (especially for journaled data mode), so be
> * cautious in our locking. */
> @@ -2014,6 +2026,9 @@ void jbd2_journal_invalidatepage(journal_t *journal,
> unsigned int next_off = curr_off + bh->b_size;
> next = bh->b_this_page;
>
> + if (next_off > stop)
> + return;
> +
> if (offset <= curr_off) {
> /* This block is wholly outside the truncation point */
> lock_buffer(bh);
> diff --git a/include/linux/jbd2.h b/include/linux/jbd2.h
> index 3efc43f..21288fa 100644
> --- a/include/linux/jbd2.h
> +++ b/include/linux/jbd2.h
> @@ -1101,6 +1101,8 @@ extern int jbd2_journal_forget (handle_t *, struct buffer_head *);
> extern void journal_sync_buffer (struct buffer_head *);
> extern void jbd2_journal_invalidatepage(journal_t *,
> struct page *, unsigned long);
> +extern void jbd2_journal_invalidatepage_range(journal_t *, struct page *,
> + unsigned int, unsigned int);
> extern int jbd2_journal_try_to_free_buffers(journal_t *, struct page *, gfp_t);
> extern int jbd2_journal_stop(handle_t *);
> extern int jbd2_journal_flush (journal_t *);
> --
> 1.7.7.6
>
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