From: Sargun Dhillon <sargun@sargun.me>
To: linux-unionfs@vger.kernel.org, miklos@szeredi.hu,
Alexander Viro <viro@zeniv.linux.org.uk>,
Amir Goldstein <amir73il@gmail.com>
Cc: Sargun Dhillon <sargun@sargun.me>,
Giuseppe Scrivano <gscrivan@redhat.com>,
Vivek Goyal <vgoyal@redhat.com>,
Daniel J Walsh <dwalsh@redhat.com>,
linux-fsdevel@vger.kernel.org,
David Howells <dhowells@redhat.com>
Subject: [PATCH v1 3/3] overlay: Add rudimentary checking of writeback errseq on volatile remount
Date: Wed, 25 Nov 2020 02:46:21 -0800 [thread overview]
Message-ID: <20201125104621.18838-4-sargun@sargun.me> (raw)
In-Reply-To: <20201125104621.18838-1-sargun@sargun.me>
Volatile remounts validate the following at the moment:
* Has the module been reloaded / the system rebooted
* Has the workdir been remounted
This adds a new check for errors detected via the superblock's
errseq_t. At mount time, the errseq_t is snapshotted to disk,
and upon remount it's re-verified. This allows for kernel-level
detection of errors without forcing userspace to perform a
sync and allows for the hidden detection of writeback errors.
Signed-off-by: Sargun Dhillon <sargun@sargun.me>
---
fs/overlayfs/overlayfs.h | 1 +
fs/overlayfs/readdir.c | 6 ++++++
fs/overlayfs/super.c | 1 +
3 files changed, 8 insertions(+)
diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h
index de694ee99d7c..e8a711953b64 100644
--- a/fs/overlayfs/overlayfs.h
+++ b/fs/overlayfs/overlayfs.h
@@ -85,6 +85,7 @@ struct ovl_volatile_info {
*/
uuid_t ovl_boot_id; /* Must stay first member */
u64 s_instance_id;
+ errseq_t errseq; /* Implemented as a u32 */
} __packed;
/*
diff --git a/fs/overlayfs/readdir.c b/fs/overlayfs/readdir.c
index 4e3e2bc3ea43..2bb0641ecbbd 100644
--- a/fs/overlayfs/readdir.c
+++ b/fs/overlayfs/readdir.c
@@ -1109,6 +1109,12 @@ static int ovl_verify_volatile_info(struct ovl_fs *ofs,
return -EINVAL;
}
+ err = errseq_check(&volatiledir->d_sb->s_wb_err, info.errseq);
+ if (err) {
+ pr_debug("Workdir filesystem reports errors: %d\n", err);
+ return -EINVAL;
+ }
+
return 1;
}
diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
index 9a1b07907662..49dee41ec125 100644
--- a/fs/overlayfs/super.c
+++ b/fs/overlayfs/super.c
@@ -1248,6 +1248,7 @@ static int ovl_set_volatile_info(struct ovl_fs *ofs, struct dentry *volatiledir)
int err;
struct ovl_volatile_info info = {
.s_instance_id = volatiledir->d_sb->s_instance_id,
+ .errseq = errseq_sample(&volatiledir->d_sb->s_wb_err),
};
uuid_copy(&info.ovl_boot_id, &ovl_boot_id);
--
2.25.1
next prev parent reply other threads:[~2020-11-25 10:46 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-25 10:46 [PATCH v1 0/3] Make overlayfs volatile mounts reusable Sargun Dhillon
2020-11-25 10:46 ` [PATCH v1 1/3] fs: Add s_instance_id field to superblock for unique identification Sargun Dhillon
2020-11-25 10:46 ` [PATCH v1 2/3] overlay: Add the ability to remount volatile directories when safe Sargun Dhillon
2020-11-25 12:49 ` kernel test robot
2020-11-25 13:23 ` kernel test robot
2020-11-25 13:29 ` kernel test robot
2020-11-25 13:58 ` Amir Goldstein
2020-11-25 14:43 ` Vivek Goyal
2020-11-25 15:29 ` Sargun Dhillon
2020-11-25 18:17 ` Vivek Goyal
2020-11-25 18:31 ` Sargun Dhillon
2020-11-25 18:43 ` Vivek Goyal
2020-11-25 18:47 ` Sargun Dhillon
2020-11-25 18:52 ` Vivek Goyal
2020-11-25 19:37 ` Amir Goldstein
2020-11-25 10:46 ` Sargun Dhillon [this message]
2020-11-25 14:03 ` [PATCH v1 3/3] overlay: Add rudimentary checking of writeback errseq on volatile remount Amir Goldstein
2020-11-25 15:36 ` Vivek Goyal
2020-11-25 15:52 ` Amir Goldstein
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