Hi Xie Miao:
I cannot understand the btrfs_decode_error(). why you chose the
three errnos? what about others? eager for Ur replay. Thanks!!
---
Best Regards,
Liu Wenyi
2010/11/25, Miao Xie <miaox@xxxxxxxxxxxxxx>:
> From: Liu Bo <liubo2009@xxxxxxxxxxxxxx>
>
> This patch provide a new error handle interface for those errors that
> handled
> by current BUG_ONs.
>
> In order to protect btrfs from panic, when it comes to those BUG_ON errors,
> the interface forces btrfs readonly and saves the FS state to disk. And the
> filesystem can be umounted, although with some warning in kernel dmesg.
> Then btrfsck is helpful to recover btrfs.
>
> Signed-off-by: Liu Bo <liubo2009@xxxxxxxxxxxxxx>
> Signed-off-by: Miao Xie <miaox@xxxxxxxxxxxxxx>
> ---
> fs/btrfs/ctree.h | 8 +++++
> fs/btrfs/super.c | 88
> ++++++++++++++++++++++++++++++++++++++++++++++++++++++
> 2 files changed, 96 insertions(+), 0 deletions(-)
>
> diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
> index 78b4c34..ccf6aaf 100644
> --- a/fs/btrfs/ctree.h
> +++ b/fs/btrfs/ctree.h
> @@ -2554,6 +2554,14 @@ ssize_t btrfs_listxattr(struct dentry *dentry, char
> *buffer, size_t size);
> /* super.c */
> int btrfs_parse_options(struct btrfs_root *root, char *options);
> int btrfs_sync_fs(struct super_block *sb, int wait);
> +void __btrfs_std_error(struct btrfs_fs_info *fs_info, const char *function,
> + unsigned int line, int errno);
> +
> +#define btrfs_std_error(fs_info, errno) \
> +do { \
> + if ((errno)) \
> + __btrfs_std_error((fs_info), __func__, __LINE__, (errno));\
> +} while (0)
>
> /* acl.c */
> #ifdef CONFIG_BTRFS_FS_POSIX_ACL
> diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
> index 8299a25..48fac6e 100644
> --- a/fs/btrfs/super.c
> +++ b/fs/btrfs/super.c
> @@ -54,6 +54,94 @@
>
> static const struct super_operations btrfs_super_ops;
>
> +static const char *btrfs_decode_error(struct btrfs_fs_info *fs_info, int
> errno,
> + char nbuf[16])
> +{
> + char *errstr = NULL;
> +
> + switch (errno) {
> + case -EIO:
> + errstr = "IO failure";
> + break;
> + case -ENOMEM:
> + errstr = "Out of memory";
> + break;
> + case -EROFS:
> + errstr = "Readonly filesystem";
> + break;
> + default:
> + if (nbuf) {
> + if (snprintf(nbuf, 16, "error %d", -errno) >= 0)
> + errstr = nbuf;
> + }
> + break;
> + }
> +
> + return errstr;
> +}
> +
> +static void __save_error_info(struct btrfs_fs_info *fs_info)
> +{
> + struct btrfs_super_block *disk_super = &fs_info->super_copy;
> +
> + fs_info->fs_state = BTRFS_SUPER_FLAG_ERROR;
> + disk_super->flags &= cpu_to_le64(~BTRFS_SUPER_FLAG_VALID);
> + disk_super->flags |= cpu_to_le64(BTRFS_SUPER_FLAG_ERROR);
> +
> + mutex_lock(&fs_info->trans_mutex);
> +
> + memcpy(&fs_info->super_for_commit, disk_super,
> + sizeof(fs_info->super_for_commit));
> +
> + mutex_unlock(&fs_info->trans_mutex);
> +}
> +
> +static void save_error_info(struct btrfs_fs_info *fs_info)
> +{
> + __save_error_info(fs_info);
> + write_ctree_super(NULL, btrfs_sb(fs_info->sb), 0);
> +}
> +
> +/* btrfs handle error by forcing the filesystem readonly */
> +static void btrfs_handle_error(struct btrfs_fs_info *fs_info)
> +{
> + struct super_block *sb = fs_info->sb;
> +
> + if (sb->s_flags & MS_RDONLY)
> + return;
> +
> + if (fs_info->fs_state & BTRFS_SUPER_FLAG_ERROR) {
> + sb->s_flags |= MS_RDONLY;
> + printk(KERN_INFO "btrfs is forced readonly\n");
> + }
> +}
> +
> +/*
> + * __btrfs_std_error decodes expected errors from the caller and
> + * invokes the approciate error response.
> + */
> +void __btrfs_std_error(struct btrfs_fs_info *fs_info, const char *function,
> + unsigned int line, int errno)
> +{
> + struct super_block *sb = fs_info->sb;
> + char nbuf[16];
> + const char *errstr;
> +
> + /*
> + * Special case: if the error is EROFS, and we're already
> + * under MS_RDONLY, then it is safe here.
> + */
> + if (errno == -EROFS && (sb->s_flags & MS_RDONLY))
> + return;
> +
> + errstr = btrfs_decode_error(fs_info, errno, nbuf);
> + printk(KERN_CRIT "BTRFS error (device %s) in %s:%d: %s\n",
> + sb->s_id, function, line, errstr);
> + save_error_info(fs_info);
> +
> + btrfs_handle_error(fs_info);
> +}
> +
> static void btrfs_put_super(struct super_block *sb)
> {
> struct btrfs_root *root = btrfs_sb(sb);
> --
> 1.7.0.1
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