All of lore.kernel.org
 help / color / mirror / Atom feed
From: Greg Kurz <groug@kaod.org>
To: Miklos Szeredi <miklos@szeredi.hu>
Cc: linux-kernel@vger.kernel.org, Max Reitz <mreitz@redhat.com>,
	linux-fsdevel@vger.kernel.org, virtio-fs@redhat.com,
	Vivek Goyal <vgoyal@redhat.com>, Greg Kurz <groug@kaod.org>
Subject: [PATCH v2 4/7] fuse: Add dedicated filesystem context ops for submounts
Date: Fri,  4 Jun 2021 18:11:53 +0200	[thread overview]
Message-ID: <20210604161156.408496-5-groug@kaod.org> (raw)
In-Reply-To: <20210604161156.408496-1-groug@kaod.org>

The creation of a submount is open-coded in fuse_dentry_automount().
This brings a lot of complexity and we recently had to fix bugs
because we weren't setting SB_BORN or because we were unlocking
sb->s_umount before sb was fully configured. Most of these could
have been avoided by using the mount API instead of open-coding.

Basically, this means coming up with a proper ->get_tree()
implementation for submounts and call vfs_get_tree(), or better
fc_mount().

The creation of the superblock for submounts is quite different from
the root mount. Especially, it doesn't require to allocate a FUSE
filesystem context, nor to parse parameters.

Introduce a dedicated context ops for submounts to make this clear.
This is just a placeholder for now, fuse_get_tree_submount() will
be populated in a subsequent patch.

Only visible change is that we stop allocating/freeing a useless FUSE
filesystem context with submounts.

Signed-off-by: Greg Kurz <groug@kaod.org>
---
 fs/fuse/fuse_i.h    |  5 +++++
 fs/fuse/inode.c     | 16 ++++++++++++++++
 fs/fuse/virtio_fs.c |  3 +++
 3 files changed, 24 insertions(+)

diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index 7e463e220053..862ad317bc89 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -1097,6 +1097,11 @@ int fuse_fill_super_submount(struct super_block *sb,
  */
 bool fuse_mount_remove(struct fuse_mount *fm);
 
+/*
+ * Setup context ops for submounts
+ */
+int fuse_init_fs_context_submount(struct fs_context *fsc);
+
 /*
  * Shut down the connection (possibly sending DESTROY request).
  */
diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
index 393e36b74dc4..fa96a3762ea2 100644
--- a/fs/fuse/inode.c
+++ b/fs/fuse/inode.c
@@ -1313,6 +1313,22 @@ int fuse_fill_super_submount(struct super_block *sb,
 	return 0;
 }
 
+static int fuse_get_tree_submount(struct fs_context *fsc)
+{
+	return 0;
+}
+
+static const struct fs_context_operations fuse_context_submount_ops = {
+	.get_tree	= fuse_get_tree_submount,
+};
+
+int fuse_init_fs_context_submount(struct fs_context *fsc)
+{
+	fsc->ops = &fuse_context_submount_ops;
+	return 0;
+}
+EXPORT_SYMBOL_GPL(fuse_init_fs_context_submount);
+
 int fuse_fill_super_common(struct super_block *sb, struct fuse_fs_context *ctx)
 {
 	struct fuse_dev *fud = NULL;
diff --git a/fs/fuse/virtio_fs.c b/fs/fuse/virtio_fs.c
index bcb8a02e2d8b..e68467cc765c 100644
--- a/fs/fuse/virtio_fs.c
+++ b/fs/fuse/virtio_fs.c
@@ -1496,6 +1496,9 @@ static int virtio_fs_init_fs_context(struct fs_context *fsc)
 {
 	struct fuse_fs_context *ctx;
 
+	if (fsc->purpose == FS_CONTEXT_FOR_SUBMOUNT)
+		return fuse_init_fs_context_submount(fsc);
+
 	ctx = kzalloc(sizeof(struct fuse_fs_context), GFP_KERNEL);
 	if (!ctx)
 		return -ENOMEM;
-- 
2.31.1


  parent reply	other threads:[~2021-06-04 16:12 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-04 16:11 [PATCH v2 0/7] fuse: Some fixes " Greg Kurz
2021-06-04 16:11 ` [PATCH v2 1/7] fuse: Fix crash in fuse_dentry_automount() error path Greg Kurz
2021-06-04 16:11 ` [PATCH v2 2/7] fuse: Fix crash if superblock of submount gets killed early Greg Kurz
2021-06-08 15:08   ` Max Reitz
2021-06-04 16:11 ` [PATCH v2 3/7] fuse: Fix infinite loop in sget_fc() Greg Kurz
2021-06-08 15:12   ` Max Reitz
2021-06-04 16:11 ` Greg Kurz [this message]
2021-06-08 15:25   ` [PATCH v2 4/7] fuse: Add dedicated filesystem context ops for submounts Max Reitz
2021-06-04 16:11 ` [PATCH v2 5/7] fuse: Call vfs_get_tree() " Greg Kurz
2021-06-08 15:40   ` Max Reitz
2021-06-04 16:11 ` [PATCH v2 6/7] fuse: Switch to fc_mount() " Greg Kurz
2021-06-08 15:51   ` Max Reitz
2021-06-09  7:45     ` Greg Kurz
2021-06-11 14:44       ` Miklos Szeredi
2021-06-04 16:11 ` [PATCH v2 7/7] fuse: Make fuse_fill_super_submount() static Greg Kurz
2021-06-08 15:52 ` [PATCH v2 0/7] fuse: Some fixes for submounts Max Reitz
2021-06-09  7:46   ` Greg Kurz

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20210604161156.408496-5-groug@kaod.org \
    --to=groug@kaod.org \
    --cc=linux-fsdevel@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=miklos@szeredi.hu \
    --cc=mreitz@redhat.com \
    --cc=vgoyal@redhat.com \
    --cc=virtio-fs@redhat.com \
    --subject='Re: [PATCH v2 4/7] fuse: Add dedicated filesystem context ops for submounts' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.