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List: linux-ext4
Subject: Re: [PATCH] ext4: restart ext4_ext_remove_space() after
From: Jan Kara <jack () suse ! cz>
Date: 2010-04-26 16:09:07
Message-ID: 20100426160906.GF3673 () quack ! suse ! cz
[Download RAW message or body]
On Thu 22-04-10 08:31:11, Dmitry Monakhov wrote:
> If i_data_sem was internally dropped due to transaction restart, it is
> necessary to restart path look-up because extents tree was possibly
> modified by ext4_get_block().
>
> https://bugzilla.kernel.org/show_bug.cgi?id=15827
Nice spotting. The patch looks good to me.
Acked-by: Jan Kara <jack@suse.cz>
Honza
>
> Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
> ---
> fs/ext4/ext4.h | 1 +
> fs/ext4/extents.c | 18 +++++++++++++-----
> 2 files changed, 14 insertions(+), 5 deletions(-)
>
> diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
> index 6641c58..c69efb2 100644
> --- a/fs/ext4/ext4.h
> +++ b/fs/ext4/ext4.h
> @@ -1089,6 +1089,7 @@ enum {
> EXT4_STATE_DA_ALLOC_CLOSE, /* Alloc DA blks on close */
> EXT4_STATE_EXT_MIGRATE, /* Inode is migrating */
> EXT4_STATE_DIO_UNWRITTEN, /* need convert on dio done*/
> + EXT4_STATE_EXT_TRUNC, /* truncate is in progress, modified under i_data_sem */
> };
>
> #define EXT4_INODE_BIT_FNS(name, field) \
> diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
> index 4fa103c..6856272 100644
> --- a/fs/ext4/extents.c
> +++ b/fs/ext4/extents.c
> @@ -107,11 +107,8 @@ static int ext4_ext_truncate_extend_restart(handle_t *handle,
> if (err <= 0)
> return err;
> err = ext4_truncate_restart_trans(handle, inode, needed);
> - /*
> - * We have dropped i_data_sem so someone might have cached again
> - * an extent we are going to truncate.
> - */
> - ext4_ext_invalidate_cache(inode);
> + if (!err && !ext4_test_inode_state(inode, EXT4_STATE_EXT_TRUNC))
> + err = -EAGAIN;
>
> return err;
> }
> @@ -2370,12 +2367,15 @@ static int ext4_ext_remove_space(struct inode *inode, ext4_lblk_t start)
> if (IS_ERR(handle))
> return PTR_ERR(handle);
>
> +again:
> ext4_ext_invalidate_cache(inode);
>
> /*
> * We start scanning from right side, freeing all the blocks
> * after i_size and walking into the tree depth-wise.
> */
> + ext4_set_inode_state(inode, EXT4_STATE_EXT_TRUNC);
> + depth = ext_depth(inode);
> path = kzalloc(sizeof(struct ext4_ext_path) * (depth + 1), GFP_NOFS);
> if (path == NULL) {
> ext4_journal_stop(handle);
> @@ -2480,6 +2480,11 @@ static int ext4_ext_remove_space(struct inode *inode, ext4_lblk_t start)
> out:
> ext4_ext_drop_refs(path);
> kfree(path);
> + if (err == EAGAIN) {
> + err = 0;
> + goto again;
> + }
> + ext4_clear_inode_state(inode, EXT4_STATE_EXT_TRUNC);
> ext4_journal_stop(handle);
>
> return err;
> @@ -3338,6 +3343,9 @@ int ext4_ext_get_blocks(handle_t *handle, struct inode *inode,
> ext_debug("blocks %u/%u requested for inode %lu\n",
> iblock, max_blocks, inode->i_ino);
>
> + if (unlikely((flags & EXT4_GET_BLOCKS_CREATE)) &&
> + ext4_test_inode_state(inode, EXT4_STATE_EXT_TRUNC))
> + ext4_clear_inode_state(inode, EXT4_STATE_EXT_TRUNC);
> /* check in cache */
> cache_type = ext4_ext_in_cache(inode, iblock, &newex);
> if (cache_type) {
> --
> 1.6.6.1
>
--
Jan Kara <jack@suse.cz>
SUSE Labs, CR
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