On Fri, 16 Sep 2011, Li Zefan wrote:
> It's a bug in commit f81c9cdc567cd3160ff9e64868d9a1a7ee226480
> (Btrfs: truncate pages from clone ioctl target range)
>
> We should pass the dest range to the truncate function, but not the
> src range.
Sigh... yes.
> Also move the function before locking extent state.
Hmm, any reason? i_mutex protects us from a racing write(2), but what
about a racing mmap()? e.g.
cloner: truncates dest pages
writer: mmap -> page_mkwrite locks extent, creates new dirty page, unlocks
cloner: locks extent, clones, unlocks extent
sage
>
> Signed-off-by: Li Zefan <lizf@xxxxxxxxxxxxxx>
> ---
> fs/btrfs/ioctl.c | 8 ++++----
> 1 files changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
> index 5492bb3..f6af8b0 100644
> --- a/fs/btrfs/ioctl.c
> +++ b/fs/btrfs/ioctl.c
> @@ -2237,6 +2237,10 @@ static noinline long btrfs_ioctl_clone(struct file *file, unsigned long srcfd,
> goto out_unlock;
> }
>
> + /* truncate page cache pages from target inode range */
> + truncate_inode_pages_range(&inode->i_data, destoff,
> + PAGE_CACHE_ALIGN(destoff + len) - 1);
> +
> /* do any pending delalloc/csum calc on src, one way or
> another, and lock file content */
> while (1) {
> @@ -2253,10 +2257,6 @@ static noinline long btrfs_ioctl_clone(struct file *file, unsigned long srcfd,
> btrfs_wait_ordered_range(src, off, len);
> }
>
> - /* truncate page cache pages from target inode range */
> - truncate_inode_pages_range(&inode->i_data, off,
> - ALIGN(off + len, PAGE_CACHE_SIZE) - 1);
> -
> /* clone data */
> key.objectid = btrfs_ino(src);
> key.type = BTRFS_EXTENT_DATA_KEY;
> --
> 1.7.3.1
>
>
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