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| author | Sage Weil <sage@newdream.net> | 2011-07-26 11:31:26 -0700 |
|---|---|---|
| committer | Sage Weil <sage@newdream.net> | 2011-07-26 11:31:26 -0700 |
| commit | d79698da32b317e96216236f265a9b72b78ae568 (patch) | |
| tree | 97f98e83c699794d6a5d979688587fbfdbba2ba7 | |
| parent | 41b02e1f9bb87b07d792b64aaeb7af3d00d69cd2 (diff) | |
| download | linux-d79698da32b317e96216236f265a9b72b78ae568.tar.gz linux-d79698da32b317e96216236f265a9b72b78ae568.tar.bz2 linux-d79698da32b317e96216236f265a9b72b78ae568.zip | |
ceph: document unlocked d_parent accesses
For the most part we don't care about racing with rename when directing
MDS requests; either the old or new parent is fine. Document that, and
do some minor cleanup.
Reviewed-by: Yehuda Sadeh <yehuda@hq.newdream.net>
Signed-off-by: Sage Weil <sage@newdream.net>
| -rw-r--r-- | fs/ceph/dir.c | 2 | ||||
| -rw-r--r-- | fs/ceph/mds_client.c | 13 |
2 files changed, 11 insertions, 4 deletions
diff --git a/fs/ceph/dir.c b/fs/ceph/dir.c index 7263f825d426..852ff8600ac9 100644 --- a/fs/ceph/dir.c +++ b/fs/ceph/dir.c @@ -506,7 +506,7 @@ int ceph_handle_snapdir(struct ceph_mds_request *req, struct dentry *dentry, int err) { struct ceph_fs_client *fsc = ceph_sb_to_client(dentry->d_sb); - struct inode *parent = dentry->d_parent->d_inode; + struct inode *parent = dentry->d_parent->d_inode; /* we hold i_mutex */ /* .snap dir? */ if (err == -ENOENT && diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c index 66a8939cc518..fee028b5332e 100644 --- a/fs/ceph/mds_client.c +++ b/fs/ceph/mds_client.c @@ -621,6 +621,12 @@ static void __unregister_request(struct ceph_mds_client *mdsc, */ struct dentry *get_nonsnap_parent(struct dentry *dentry) { + /* + * we don't need to worry about protecting the d_parent access + * here because we never renaming inside the snapped namespace + * except to resplice to another snapdir, and either the old or new + * result is a valid result. + */ while (!IS_ROOT(dentry) && ceph_snap(dentry->d_inode) != CEPH_NOSNAP) dentry = dentry->d_parent; return dentry; @@ -656,7 +662,9 @@ static int __choose_mds(struct ceph_mds_client *mdsc, if (req->r_inode) { inode = req->r_inode; } else if (req->r_dentry) { - struct inode *dir = req->r_dentry->d_parent->d_inode; + /* ignore race with rename; old or new d_parent is okay */ + struct dentry *parent = req->r_dentry->d_parent; + struct inode *dir = parent->d_inode; if (dir->i_sb != mdsc->fsc->sb) { /* not this fs! */ @@ -664,8 +672,7 @@ static int __choose_mds(struct ceph_mds_client *mdsc, } else if (ceph_snap(dir) != CEPH_NOSNAP) { /* direct snapped/virtual snapdir requests * based on parent dir inode */ - struct dentry *dn = - get_nonsnap_parent(req->r_dentry->d_parent); + struct dentry *dn = get_nonsnap_parent(parent); inode = dn->d_inode; dout("__choose_mds using nonsnap parent %p\n", inode); } else if (req->r_dentry->d_inode) { |