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authorMax Reitz <mreitz@redhat.com>2020-09-09 20:40:25 +0200
committerDr. David Alan Gilbert <dgilbert@redhat.com>2020-10-26 18:35:32 +0000
commiteba8b096c17c5a74c5a00af4cf476a9b1b4d7393 (patch)
tree92b9a3739608d52486f3652e94f5f7d6df3482a0 /tools
parentede24b6be798000bbf554891e5b54a0f4848897f (diff)
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virtiofsd: Store every lo_inode's parent_dev
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>
Diffstat (limited to 'tools')
-rw-r--r--tools/virtiofsd/passthrough_ll.c17
1 files changed, 17 insertions, 0 deletions
diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c
index a0beb98..4188bf3 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);