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SubjectRe: ext4 deadlocks
Kalpak Shah wrote:

> ext4_xattr_set_handle() eventually ends up calling
> ext4_mark_inode_dirty() which tries to expand the inode by shifting the
> EAs. This leads to the xattr_sem being downed again and leading to a
> deadlock.
>
> This patch makes sure that if ext4_xattr_set_handle() is in the
> call-chain, ext4_mark_inode_dirty() will not expand the inode.
>
> Signed-off-by: Kalpak Shah <kalpak.shah@sun.com>

Yes, this fixes my testcase. Thanks, Kalpak.

-Eric

> Index: linux-2.6.27-rc7/fs/ext4/xattr.c
> ===================================================================
> --- linux-2.6.27-rc7.orig/fs/ext4/xattr.c
> +++ linux-2.6.27-rc7/fs/ext4/xattr.c
> @@ -959,6 +959,7 @@ ext4_xattr_set_handle(handle_t *handle,
> struct ext4_xattr_block_find bs = {
> .s = { .not_found = -ENODATA, },
> };
> + unsigned long no_expand;
> int error;
>
> if (!name)
> @@ -966,6 +967,9 @@ ext4_xattr_set_handle(handle_t *handle,
> if (strlen(name) > 255)
> return -ERANGE;
> down_write(&EXT4_I(inode)->xattr_sem);
> + no_expand = EXT4_I(inode)->i_state & EXT4_STATE_NO_EXPAND;
> + EXT4_I(inode)->i_state |= EXT4_STATE_NO_EXPAND;
> +
> error = ext4_get_inode_loc(inode, &is.iloc);
> if (error)
> goto cleanup;
> @@ -1042,6 +1046,8 @@ ext4_xattr_set_handle(handle_t *handle,
> cleanup:
> brelse(is.iloc.bh);
> brelse(bs.bh);
> + if (no_expand == 0)
> + EXT4_I(inode)->i_state &= ~EXT4_STATE_NO_EXPAND;
> up_write(&EXT4_I(inode)->xattr_sem);
> return error;
> }
>
> Thanks,
> Kalpak
>
> --
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