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[PULL 13/16] virtiofsd: Store every lo_inode's parent_dev
From: |
Dr. David Alan Gilbert (git) |
Subject: |
[PULL 13/16] virtiofsd: Store every lo_inode's parent_dev |
Date: |
Mon, 26 Oct 2020 18:43:28 +0000 |
From: Max Reitz <mreitz@redhat.com>
We want to detect mount points in the shared tree. We report them to
the guest by setting the FUSE_ATTR_SUBMOUNT flag in fuse_attr.flags, but
because the FUSE client will create a submount for every directory that
has this flag set, we must do this only for the actual mount points.
We can detect mount points by comparing a directory's st_dev with its
parent's st_dev. To be able to do so, we need to store the parent's
st_dev in the lo_inode object.
Note that mount points need not necessarily be directories; a single
file can be a mount point as well. However, for the sake of simplicity
let us ignore any non-directory mount points for now.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Message-Id: <20200909184028.262297-6-mreitz@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
---
tools/virtiofsd/passthrough_ll.c | 17 +++++++++++++++++
1 file changed, 17 insertions(+)
diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c
index a0beb986f3..4188bf3ad2 100644
--- a/tools/virtiofsd/passthrough_ll.c
+++ b/tools/virtiofsd/passthrough_ll.c
@@ -125,6 +125,14 @@ struct lo_inode {
GHashTable *posix_locks; /* protected by lo_inode->plock_mutex */
mode_t filetype;
+
+ /*
+ * So we can detect crossmount roots
+ * (As such, this only needs to be valid for directories. Note
+ * that files can have multiple parents due to hard links, and so
+ * their parent_dev may fluctuate.)
+ */
+ dev_t parent_dev;
};
struct lo_cred {
@@ -847,6 +855,7 @@ static int lo_do_lookup(fuse_req_t req, fuse_ino_t parent,
const char *name,
g_hash_table_insert(lo->inodes, &inode->key, inode);
pthread_mutex_unlock(&lo->mutex);
}
+ inode->parent_dev = dir->key.dev;
e->ino = inode->fuse_ino;
lo_inode_put(lo, &inode);
lo_inode_put(lo, &dir);
@@ -1073,6 +1082,14 @@ static void lo_link(fuse_req_t req, fuse_ino_t ino,
fuse_ino_t parent,
fuse_log(FUSE_LOG_DEBUG, " %lli/%s -> %lli\n", (unsigned long long)parent,
name, (unsigned long long)e.ino);
+ /*
+ * No need to update inode->parent_dev, because
+ * (1) We cannot, the inode now has more than one parent,
+ * (2) Directories cannot have more than one parent, so link()
+ * does not work for them; but parent_dev only needs to be
+ * valid for directories.
+ */
+
fuse_reply_entry(req, &e);
lo_inode_put(lo, &parent_inode);
lo_inode_put(lo, &inode);
--
2.28.0
- [PULL 02/16] virtiofsd: passthrough_ll: set FUSE_LOG_INFO as default log_level, (continued)
- [PULL 02/16] virtiofsd: passthrough_ll: set FUSE_LOG_INFO as default log_level, Dr. David Alan Gilbert (git), 2020/10/26
- [PULL 03/16] virtiofsd: add container-friendly -o sandbox=chroot option, Dr. David Alan Gilbert (git), 2020/10/26
- [PULL 04/16] tools/virtiofsd: xattr name mappings: Add option, Dr. David Alan Gilbert (git), 2020/10/26
- [PULL 05/16] tools/virtiofsd: xattr name mappings: Map client xattr names, Dr. David Alan Gilbert (git), 2020/10/26
- [PULL 07/16] tools/virtiofsd: xattr name mapping examples, Dr. David Alan Gilbert (git), 2020/10/26
- [PULL 06/16] tools/virtiofsd: xattr name mappings: Map server xattr names, Dr. David Alan Gilbert (git), 2020/10/26
- [PULL 08/16] tools/virtiofsd: xattr name mappings: Simple 'map', Dr. David Alan Gilbert (git), 2020/10/26
- [PULL 09/16] linux/fuse.h: Pull in from Linux, Dr. David Alan Gilbert (git), 2020/10/26
- [PULL 11/16] virtiofsd: Add attr_flags to fuse_entry_param, Dr. David Alan Gilbert (git), 2020/10/26
- [PULL 10/16] virtiofsd: Announce FUSE_ATTR_FLAGS, Dr. David Alan Gilbert (git), 2020/10/26
- [PULL 13/16] virtiofsd: Store every lo_inode's parent_dev,
Dr. David Alan Gilbert (git) <=
- [PULL 12/16] virtiofsd: Add fuse_reply_attr_with_flags(), Dr. David Alan Gilbert (git), 2020/10/26
- [PULL 14/16] virtiofsd: Announce sub-mount points, Dr. David Alan Gilbert (git), 2020/10/26
- [PULL 15/16] tests/acceptance/boot_linux: Accept SSH pubkey, Dr. David Alan Gilbert (git), 2020/10/26
- [PULL 16/16] tests/acceptance: Add virtiofs_submounts.py, Dr. David Alan Gilbert (git), 2020/10/26
- Re: [PULL 00/16] virtiofs queue, Peter Maydell, 2020/10/27