When performing an unlink, if we have Fx on the parent directory and
Lx on the inode of the dentry being unlinked then we don't need to
wait on the reply before returning.
In that situation, just fix up the dcache and link count and return
immediately after issuing the call to the MDS. This does mean that we
need to hold an extra reference to the inode being unlinked, and extra
references to the caps to avoid races. Put those references in the
r_callback routine.
If the operation ends up failing, then set a writeback error on the
directory inode that can be fetched later by an fsync on the dir.
Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx>
---
fs/ceph/caps.c | 22 ++++++++++++++++++++++
fs/ceph/dir.c | 38 +++++++++++++++++++++++++++++++++++---
fs/ceph/super.h | 1 +
3 files changed, 58 insertions(+), 3 deletions(-)
diff --git a/fs/ceph/caps.c b/fs/ceph/caps.c
index d022e15c8378..8fbb09c761a7 100644
--- a/fs/ceph/caps.c
+++ b/fs/ceph/caps.c
@@ -2682,6 +2682,28 @@ static int try_get_cap_refs(struct ceph_inode_info *ci, int need, int want,
return ret;
}
+bool ceph_get_caps_for_unlink(struct inode *dir, struct dentry *dentry)
+{
+ int err, got;
+ struct ceph_inode_info *ci = ceph_inode(d_inode(dentry));
+
+ /* Ensure we have Lx on the inode being unlinked */
+ err = try_get_cap_refs(ci, 0, CEPH_CAP_LINK_EXCL, 0, true, &got);
+ dout("Lx on %p err=%d got=%d\n", dentry, err, got);
+ if (err != 1 || !(got & CEPH_CAP_LINK_EXCL))
+ return false;
+
+ /* Do we have Fx on the dir ? */
+ err = try_get_cap_refs(ceph_inode(dir), 0, CEPH_CAP_FILE_EXCL, 0,
+ true, &got);
+ dout("Fx on %p err=%d got=%d\n", dir, err, got);
+ if (err != 1 || !(got & CEPH_CAP_FILE_EXCL)) {
+ ceph_put_cap_refs(ci, CEPH_CAP_LINK_EXCL);
+ return false;
+ }
+ return true;
+}
+
/*
* Check the offset we are writing up to against our current
* max_size. If necessary, tell the MDS we want to write to
diff --git a/fs/ceph/dir.c b/fs/ceph/dir.c
index 3eb9bc226b77..386c9439a020 100644
--- a/fs/ceph/dir.c
+++ b/fs/ceph/dir.c
@@ -1029,6 +1029,18 @@ static int ceph_link(struct dentry *old_dentry, struct inode *dir,
return err;
}
+static void ceph_async_unlink_cb(struct ceph_mds_client *mdsc,
+ struct ceph_mds_request *req)
+{
+ struct ceph_inode_info *ci = ceph_inode(req->r_old_inode);
+
+ /* If op failed, set error on parent directory */
+ mapping_set_error(req->r_parent->i_mapping, req->r_err);
+ ceph_put_cap_refs(ci, CEPH_CAP_LINK_EXCL);
+ ceph_put_cap_refs(ceph_inode(req->r_parent), CEPH_CAP_FILE_EXCL);
+ iput(req->r_old_inode);
+}
+
/*
* rmdir and unlink are differ only by the metadata op code
*/
@@ -1065,9 +1077,29 @@ static int ceph_unlink(struct inode *dir, struct dentry *dentry)
req->r_dentry_drop = CEPH_CAP_FILE_SHARED;
req->r_dentry_unless = CEPH_CAP_FILE_EXCL;
req->r_inode_drop = ceph_drop_caps_for_unlink(inode);
- err = ceph_mdsc_do_request(mdsc, dir, req);
- if (!err && !req->r_reply_info.head->is_dentry)
- d_delete(dentry);
+
+ if (op == CEPH_MDS_OP_UNLINK &&
+ ceph_get_caps_for_unlink(dir, dentry)) {
+ /* Keep LINK caps to ensure continuity over async call */
+ req->r_inode_drop &= ~(CEPH_CAP_LINK_SHARED|CEPH_CAP_LINK_EXCL);
+ req->r_callback = ceph_async_unlink_cb;
+ req->r_old_inode = d_inode(dentry);
+ ihold(req->r_old_inode);
+ err = ceph_mdsc_submit_request(mdsc, dir, req);
+ if (!err) {
+ /*
+ * We have enough caps, so we assume that the unlink
+ * will succeed. Fix up the target inode and dcache.
+ */
+ drop_nlink(inode);
+ d_delete(dentry);
+ }
+ } else {
+ err = ceph_mdsc_do_request(mdsc, dir, req);
+ if (!err && !req->r_reply_info.head->is_dentry)
+ d_delete(dentry);
+ }
+
ceph_mdsc_put_request(req);
out:
return err;
diff --git a/fs/ceph/super.h b/fs/ceph/super.h
index 3c5608f2108a..5c361dc1f47f 100644
--- a/fs/ceph/super.h
+++ b/fs/ceph/super.h
@@ -1033,6 +1033,7 @@ extern int ceph_get_caps(struct ceph_inode_info *ci, int need, int want,
loff_t endoff, int *got, struct page **pinned_page);
extern int ceph_try_get_caps(struct ceph_inode_info *ci,
int need, int want, bool nonblock, int *got);
+extern bool ceph_get_caps_for_unlink(struct inode *dir, struct dentry *dentry);
/* for counting open files by mode */
extern void __ceph_get_fmode(struct ceph_inode_info *ci, int mode);
--
2.20.1
