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Date: Tue, 31 Mar 2009 11:38:19 +0200
From: Jan Kara <jack@...e.cz>
To: "Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>
Cc: tytso@....edu, linux-ext4@...r.kernel.org
Subject: Re: [PATCH 2/2] [PATCH] ext4: truncate the file properly if we
fail to copy data from userspace.
On Tue 31-03-09 14:59:26, Aneesh Kumar K.V wrote:
> In generic_perform_write if we fail to copy the user data we don't
> update the inode->i_size. We should truncate the file in the above case
> so that we don't have blocks allocated outside inode->i_size. Add
> the inode to orphan list in the same transaction as block allocation
> This ensures that if we crash in between the recovery would do the truncate.
>
> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@...ux.vnet.ibm.com>
> CC: Jan Kara <jack@...e.cz>
This patch looks fine as well.
Reviewed-by: Jan Kara <jack@...e.cz>
Honza
> ---
> fs/ext4/inode.c | 103 +++++++++++++++++++++++++++++++++++++++++--------------
> 1 files changed, 77 insertions(+), 26 deletions(-)
>
> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> index 074185f..3997999 100644
> --- a/fs/ext4/inode.c
> +++ b/fs/ext4/inode.c
> @@ -1505,6 +1505,52 @@ static int write_end_fn(handle_t *handle, struct buffer_head *bh)
> return ext4_handle_dirty_metadata(handle, NULL, bh);
> }
>
> +static int ext4_generic_write_end(struct file *file,
> + struct address_space *mapping,
> + loff_t pos, unsigned len, unsigned copied,
> + struct page *page, void *fsdata)
> +{
> + int i_size_changed = 0;
> + struct inode *inode = mapping->host;
> + handle_t *handle = ext4_journal_current_handle();
> +
> + copied = block_write_end(file, mapping, pos, len, copied, page, fsdata);
> +
> + /*
> + * No need to use i_size_read() here, the i_size
> + * cannot change under us because we hold i_mutex.
> + *
> + * But it's important to update i_size while still holding page lock:
> + * page writeout could otherwise come in and zero beyond i_size.
> + */
> + if (pos + copied > inode->i_size) {
> + i_size_write(inode, pos + copied);
> + i_size_changed = 1;
> + }
> +
> + if (pos + copied > EXT4_I(inode)->i_disksize) {
> + /* We need to mark inode dirty even if
> + * new_i_size is less that inode->i_size
> + * bu greater than i_disksize.(hint delalloc)
> + */
> + ext4_update_i_disksize(inode, (pos + copied));
> + i_size_changed = 1;
> + }
> + unlock_page(page);
> + page_cache_release(page);
> +
> + /*
> + * Don't mark the inode dirty under page lock. First, it unnecessarily
> + * makes the holding time of page lock longer. Second, it forces lock
> + * ordering of page lock and transaction start for journaling
> + * filesystems.
> + */
> + if (i_size_changed)
> + ext4_mark_inode_dirty(handle, inode);
> +
> + return copied;
> +}
> +
> /*
> * We need to pick up the new inode size which generic_commit_write gave us
> * `file' can be NULL - eg, when called from page_symlink().
> @@ -1528,21 +1574,15 @@ static int ext4_ordered_write_end(struct file *file,
> ret = ext4_jbd2_file_inode(handle, inode);
>
> if (ret == 0) {
> - loff_t new_i_size;
> -
> - new_i_size = pos + copied;
> - if (new_i_size > EXT4_I(inode)->i_disksize) {
> - ext4_update_i_disksize(inode, new_i_size);
> - /* We need to mark inode dirty even if
> - * new_i_size is less that inode->i_size
> - * bu greater than i_disksize.(hint delalloc)
> - */
> - ext4_mark_inode_dirty(handle, inode);
> - }
> -
> - ret2 = generic_write_end(file, mapping, pos, len, copied,
> + ret2 = ext4_generic_write_end(file, mapping, pos, len, copied,
> page, fsdata);
> copied = ret2;
> + if (pos + len > inode->i_size)
> + /* if we have allocated more blocks and copied
> + * less. We will have blocks allocated outside
> + * inode->i_size. So truncate them
> + */
> + ext4_orphan_add(handle, inode);
> if (ret2 < 0)
> ret = ret2;
> }
> @@ -1550,6 +1590,9 @@ static int ext4_ordered_write_end(struct file *file,
> if (!ret)
> ret = ret2;
>
> + if (pos + len > inode->i_size)
> + vmtruncate(inode, inode->i_size);
> +
> return ret ? ret : copied;
> }
>
> @@ -1561,25 +1604,21 @@ static int ext4_writeback_write_end(struct file *file,
> handle_t *handle = ext4_journal_current_handle();
> struct inode *inode = mapping->host;
> int ret = 0, ret2;
> - loff_t new_i_size;
>
> trace_mark(ext4_writeback_write_end,
> "dev %s ino %lu pos %llu len %u copied %u",
> inode->i_sb->s_id, inode->i_ino,
> (unsigned long long) pos, len, copied);
> - new_i_size = pos + copied;
> - if (new_i_size > EXT4_I(inode)->i_disksize) {
> - ext4_update_i_disksize(inode, new_i_size);
> - /* We need to mark inode dirty even if
> - * new_i_size is less that inode->i_size
> - * bu greater than i_disksize.(hint delalloc)
> - */
> - ext4_mark_inode_dirty(handle, inode);
> - }
> -
> - ret2 = generic_write_end(file, mapping, pos, len, copied,
> + ret2 = ext4_generic_write_end(file, mapping, pos, len, copied,
> page, fsdata);
> copied = ret2;
> + if (pos + len > inode->i_size)
> + /* if we have allocated more blocks and copied
> + * less. We will have blocks allocated outside
> + * inode->i_size. So truncate them
> + */
> + ext4_orphan_add(handle, inode);
> +
> if (ret2 < 0)
> ret = ret2;
>
> @@ -1587,6 +1626,9 @@ static int ext4_writeback_write_end(struct file *file,
> if (!ret)
> ret = ret2;
>
> + if (pos + len > inode->i_size)
> + vmtruncate(inode, inode->i_size);
> +
> return ret ? ret : copied;
> }
>
> @@ -1631,10 +1673,19 @@ static int ext4_journalled_write_end(struct file *file,
> }
>
> unlock_page(page);
> + page_cache_release(page);
> + if (pos + len > inode->i_size)
> + /* if we have allocated more blocks and copied
> + * less. We will have blocks allocated outside
> + * inode->i_size. So truncate them
> + */
> + ext4_orphan_add(handle, inode);
> +
> ret2 = ext4_journal_stop(handle);
> if (!ret)
> ret = ret2;
> - page_cache_release(page);
> + if (pos + len > inode->i_size)
> + vmtruncate(inode, inode->i_size);
>
> return ret ? ret : copied;
> }
> --
> 1.6.2.1.404.gb0085.dirty
>
--
Jan Kara <jack@...e.cz>
SUSE Labs, CR
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