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author | Max Reitz <mreitz@redhat.com> | 2020-09-09 20:40:25 +0200 |
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committer | Dr. David Alan Gilbert <dgilbert@redhat.com> | 2020-10-26 18:35:32 +0000 |
commit | eba8b096c17c5a74c5a00af4cf476a9b1b4d7393 (patch) | |
tree | 92b9a3739608d52486f3652e94f5f7d6df3482a0 /tools | |
parent | ede24b6be798000bbf554891e5b54a0f4848897f (diff) | |
download | qemu-eba8b096c17c5a74c5a00af4cf476a9b1b4d7393.zip qemu-eba8b096c17c5a74c5a00af4cf476a9b1b4d7393.tar.gz qemu-eba8b096c17c5a74c5a00af4cf476a9b1b4d7393.tar.bz2 |
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.c | 17 |
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); |