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Date: Mon, 8 Jun 2009 21:23:57 +0200
From: Jan Kara <jack@...e.cz>
To: Theodore Tso <tytso@....edu>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>,
cmm@...ibm.com, sandeen@...hat.com, linux-ext4@...r.kernel.org,
Jan Kara <jack@...e.cz>
Subject: Re: [PATCH -V2 2/2] ext4: truncate the file properly if we fail to
copy data from userspace
Hi,
On Mon 08-06-09 15:14:20, Theodore Tso wrote:
> On Mon, Jun 08, 2009 at 10:13:57PM +0530, Aneesh Kumar K.V wrote:
> > I think i both the case Jan's patch
> > allocate-blocks-correctly-with-subpage-blocksize need an update ? Since you have put
> > the patch before Jan's changes.
>
> OK, here's how I updated Jan's patch. I'm going to assume that we'll
> submit the ext4 patch queue immediately as soon as the merge window
> opens, since my impression is Jan is still waiting for some mm
> developers to review his patch set.
Yes, no review yet :( So put my patches to the end so that they don't
block other fixes in the patch queue.
> Annesh, does this look good to you?
>
> Jan, if we go down this path, you'll need to update your ext4 patch
> with this updated one, to take into account the changes from Aneesh's
> patch.
Thanks for the patch.
Honza
> ext4: Make sure blocks are properly allocated under mmaped page even when blocksize < pagesize
>
> From: Jan Kara <jack@...e.cz>
>
> In a situation like:
> truncate(f, 1024);
> a = mmap(f, 0, 4096);
> a[0] = 'a';
> truncate(f, 4096);
>
> we end up with a dirty page which does not have all blocks allocated /
> reserved. Fix the problem by using new VFS infrastructure.
>
> Signed-off-by: Jan Kara <jack@...e.cz>
> ---
> fs/ext4/extents.c | 2 +-
> fs/ext4/inode.c | 22 ++++++++++++++++++++--
> 2 files changed, 21 insertions(+), 3 deletions(-)
>
> diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
> index 9c35a7b..f2a2591 100644
> --- a/fs/ext4/extents.c
> +++ b/fs/ext4/extents.c
> @@ -3069,7 +3069,7 @@ static void ext4_falloc_update_inode(struct inode *inode,
> */
> if (!(mode & FALLOC_FL_KEEP_SIZE)) {
> if (new_size > i_size_read(inode))
> - i_size_write(inode, new_size);
> + block_extend_i_size(inode, new_size, 0);
> if (new_size > EXT4_I(inode)->i_disksize)
> ext4_update_i_disksize(inode, new_size);
> }
> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> index f4cf46e..6450b55 100644
> --- a/fs/ext4/inode.c
> +++ b/fs/ext4/inode.c
> @@ -1491,7 +1491,7 @@ static int ext4_write_begin(struct file *file, struct address_space *mapping,
> index = pos >> PAGE_CACHE_SHIFT;
> from = pos & (PAGE_CACHE_SIZE - 1);
> to = from + len;
> -
> + block_lock_hole_extend(inode, pos);
> retry:
> handle = ext4_journal_start(inode, needed_blocks);
> if (IS_ERR(handle)) {
> @@ -1550,6 +1550,8 @@ retry:
> if (ret == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries))
> goto retry;
> out:
> + if (ret)
> + block_unlock_hole_extend(inode);
> return ret;
> }
>
> @@ -1595,6 +1597,7 @@ static int ext4_generic_write_end(struct file *file,
> }
> unlock_page(page);
> page_cache_release(page);
> + block_unlock_hole_extend(inode);
>
> /*
> * Don't mark the inode dirty under page lock. First, it unnecessarily
> @@ -1739,6 +1742,8 @@ static int ext4_journalled_write_end(struct file *file,
>
> unlock_page(page);
> page_cache_release(page);
> + block_unlock_hole_extend(inode);
> +
> if (pos + len > inode->i_size)
> /* if we have allocated more blocks and copied
> * less. We will have blocks allocated outside
> @@ -2888,6 +2893,7 @@ static int ext4_da_write_begin(struct file *file, struct address_space *mapping,
> }
> *fsdata = (void *)0;
> trace_ext4_da_write_begin(inode, pos, len, flags);
> + block_lock_hole_extend(inode, pos);
> retry:
> /*
> * With delayed allocation, we don't log the i_disksize update
> @@ -2930,6 +2936,8 @@ retry:
> if (ret == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries))
> goto retry;
> out:
> + if (ret)
> + block_unlock_hole_extend(inode);
> return ret;
> }
>
> @@ -3468,7 +3476,7 @@ static ssize_t ext4_direct_IO(int rw, struct kiocb *iocb,
> loff_t end = offset + ret;
> if (end > inode->i_size) {
> ei->i_disksize = end;
> - i_size_write(inode, end);
> + block_extend_i_size(inode, offset, ret);
> /*
> * We're going to return a positive `ret'
> * here due to non-zero-length I/O, so there's
> @@ -3513,6 +3521,7 @@ static const struct address_space_operations ext4_ordered_aops = {
> .sync_page = block_sync_page,
> .write_begin = ext4_write_begin,
> .write_end = ext4_ordered_write_end,
> + .extend_i_size = block_extend_i_size,
> .bmap = ext4_bmap,
> .invalidatepage = ext4_invalidatepage,
> .releasepage = ext4_releasepage,
> @@ -3528,6 +3537,7 @@ static const struct address_space_operations ext4_writeback_aops = {
> .sync_page = block_sync_page,
> .write_begin = ext4_write_begin,
> .write_end = ext4_writeback_write_end,
> + .extend_i_size = block_extend_i_size,
> .bmap = ext4_bmap,
> .invalidatepage = ext4_invalidatepage,
> .releasepage = ext4_releasepage,
> @@ -3543,6 +3553,7 @@ static const struct address_space_operations ext4_journalled_aops = {
> .sync_page = block_sync_page,
> .write_begin = ext4_write_begin,
> .write_end = ext4_journalled_write_end,
> + .extend_i_size = block_extend_i_size,
> .set_page_dirty = ext4_journalled_set_page_dirty,
> .bmap = ext4_bmap,
> .invalidatepage = ext4_invalidatepage,
> @@ -3558,6 +3569,7 @@ static const struct address_space_operations ext4_da_aops = {
> .sync_page = block_sync_page,
> .write_begin = ext4_da_write_begin,
> .write_end = ext4_da_write_end,
> + .extend_i_size = block_extend_i_size,
> .bmap = ext4_bmap,
> .invalidatepage = ext4_da_invalidatepage,
> .releasepage = ext4_releasepage,
> @@ -5404,6 +5416,12 @@ int ext4_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
> struct address_space *mapping = inode->i_mapping;
>
> /*
> + * Wait for extending of i_size, after this moment, next truncate /
> + * write can create holes under us but they writeprotect our page so
> + * we'll be called again to fill the hole.
> + */
> + block_wait_on_hole_extend(inode, page_offset(page));
> + /*
> * Get i_alloc_sem to stop truncates messing with the inode. We cannot
> * get i_mutex because we are already holding mmap_sem.
> */
--
Jan Kara <jack@...e.cz>
SUSE Labs, CR
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