I apologize for the slow review, Thieu. When I originally reviewed this
patch, our email infrastructure was down for maintenance, so I saved it
off in a local drafts folder. I forgot about it until you pinged me. :/
Original review below...
On Thu Jul 28, 2011 at 05:57:47PM -0700, Thieu Le <thieule@xxxxxxxxxxxx> wrote:
> eCryptfs does not allocate space in the lower file until writepage. In
> low free space situation, this leads to the application thinking the
> write succeeds but it actually fails later when the page is written out.
> This patch preallocates the space in the write path using fallocate()
> first. For lower file systems that do not support fallocate(), it falls back
> to writing the encrypted page directly to the lower file. The
> preallocation is only done for writes that extend the file.
>
> Signed-off-by: Thieu Le <thieule@xxxxxxxxxxxx>
> ---
> fs/ecryptfs/mmap.c | 26 ++++++++++++++++++++++++--
> 1 files changed, 24 insertions(+), 2 deletions(-)
>
> diff --git a/fs/ecryptfs/mmap.c b/fs/ecryptfs/mmap.c
> index 6a44148..ed0eace 100644
> --- a/fs/ecryptfs/mmap.c
> +++ b/fs/ecryptfs/mmap.c
> @@ -520,9 +520,29 @@ static int ecryptfs_write_end(struct file *file,
> goto out;
> }
> set_page_dirty(page);
> - unlock_page(page);
> - need_unlock_page = 0;
> if (pos + copied > i_size_read(ecryptfs_inode)) {
> + struct ecryptfs_inode_info *inode_info =
> + ecryptfs_inode_to_private(ecryptfs_inode);
> + loff_t offset = ecryptfs_lower_header_size(crypt_stat) + pos;
> + BUG_ON(!inode_info->lower_file);
> + rc = do_fallocate(inode_info->lower_file, 0, offset,
> + PAGE_CACHE_SIZE);
do_fallocate() isn't exported to modules:
WARNING: "do_fallocate" [fs/ecryptfs/ecryptfs.ko] undefined!
> + if (rc == -EOPNOTSUPP)
> + rc = ecryptfs_encrypt_page(page);
> + if (rc) {
> + if (rc != -ENOSPC) {
> + ecryptfs_printk(KERN_ERR,
> + "Error preallocating page "
> + "(upper index "
> + "[0x%.16lx], rc = [%d])\n",
> + index, rc);
> + }
> + goto out;
> + }
> +
> + unlock_page(page);
> + need_unlock_page = 0;
> +
> i_size_write(ecryptfs_inode, pos + copied);
> ecryptfs_printk(KERN_DEBUG, "Expanded file size to "
> "[0x%.16llx]\n",
> @@ -540,6 +560,8 @@ out:
> if (need_unlock_page)
> unlock_page(page);
> page_cache_release(page);
> + if (rc)
> + truncate_inode_pages(mapping, i_size_read(ecryptfs_inode));
This change seems to be silently fixing a separate issue (truncating
after a failed write).
I wonder if we should be using ecryptfs_truncate() here, instead? It
truncates the lower file, as well.
Tyler
> return rc;
> }
>
> --
> 1.7.3.1
>
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