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authorJeff Layton <jlayton@kernel.org>2019-04-02 22:35:56 +0300
committerIlya Dryomov <idryomov@gmail.com>2020-03-30 13:42:42 +0300
commit2ccb45462aeaf0831397b90d31d3d50a7704fa1f (patch)
treea2a9cb929402d939a9db386c7d0958985a685bbe /fs/ceph/dir.c
parent173e70e8ac0f1e7e3eb98f1ffb953e80a5cc8a5f (diff)
downloadlinux-2ccb45462aeaf0831397b90d31d3d50a7704fa1f.tar.xz
ceph: perform asynchronous unlink if we have sufficient caps
The MDS is getting a new lock-caching facility that will allow it to cache the necessary locks to allow asynchronous directory operations. Since the CEPH_CAP_FILE_* caps are currently unused on directories, we can repurpose those bits for this purpose. When performing an unlink, if we have Fx on the parent directory, and CEPH_CAP_DIR_UNLINK (aka Fr), and we know that the dentry being removed is the primary link, then then we can fire off an unlink request immediately and don't need to wait on 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. Those references are put and error handling is done in the r_callback routine. If the operation ends up failing, then set a writeback error on the directory inode, and the inode itself that can be fetched later by an fsync on the dir. The behavior of dir caps is slightly different from caps on normal files. Because these are just considered an optimization, if the session is reconnected, we will not automatically reclaim them. They are instead considered lost until we do another synchronous op in the parent directory. Async dirops are enabled via the "nowsync" mount option, which is patterned after the xfs "wsync" mount option. For now, the default is "wsync", but eventually we may flip that. Signed-off-by: Jeff Layton <jlayton@kernel.org> Reviewed-by: "Yan, Zheng" <zyan@redhat.com> Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Diffstat (limited to 'fs/ceph/dir.c')
-rw-r--r--fs/ceph/dir.c108
1 files changed, 104 insertions, 4 deletions
diff --git a/fs/ceph/dir.c b/fs/ceph/dir.c
index 5b83bda57056..ee6b319e5481 100644
--- a/fs/ceph/dir.c
+++ b/fs/ceph/dir.c
@@ -1036,6 +1036,78 @@ 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)
+{
+ int result = req->r_err ? req->r_err :
+ le32_to_cpu(req->r_reply_info.head->result);
+
+ if (result == -EJUKEBOX)
+ goto out;
+
+ /* If op failed, mark everyone involved for errors */
+ if (result) {
+ int pathlen;
+ u64 base;
+ char *path = ceph_mdsc_build_path(req->r_dentry, &pathlen,
+ &base, 0);
+
+ /* mark error on parent + clear complete */
+ mapping_set_error(req->r_parent->i_mapping, result);
+ ceph_dir_clear_complete(req->r_parent);
+
+ /* drop the dentry -- we don't know its status */
+ if (!d_unhashed(req->r_dentry))
+ d_drop(req->r_dentry);
+
+ /* mark inode itself for an error (since metadata is bogus) */
+ mapping_set_error(req->r_old_inode->i_mapping, result);
+
+ pr_warn("ceph: async unlink failure path=(%llx)%s result=%d!\n",
+ base, IS_ERR(path) ? "<<bad>>" : path, result);
+ ceph_mdsc_free_path(path, pathlen);
+ }
+out:
+ iput(req->r_old_inode);
+ ceph_mdsc_release_dir_caps(req);
+}
+
+static int get_caps_for_async_unlink(struct inode *dir, struct dentry *dentry)
+{
+ struct ceph_inode_info *ci = ceph_inode(dir);
+ struct ceph_dentry_info *di;
+ int got = 0, want = CEPH_CAP_FILE_EXCL | CEPH_CAP_DIR_UNLINK;
+
+ spin_lock(&ci->i_ceph_lock);
+ if ((__ceph_caps_issued(ci, NULL) & want) == want) {
+ ceph_take_cap_refs(ci, want, false);
+ got = want;
+ }
+ spin_unlock(&ci->i_ceph_lock);
+
+ /* If we didn't get anything, return 0 */
+ if (!got)
+ return 0;
+
+ spin_lock(&dentry->d_lock);
+ di = ceph_dentry(dentry);
+ /*
+ * - We are holding Fx, which implies Fs caps.
+ * - Only support async unlink for primary linkage
+ */
+ if (atomic_read(&ci->i_shared_gen) != di->lease_shared_gen ||
+ !(di->flags & CEPH_DENTRY_PRIMARY_LINK))
+ want = 0;
+ spin_unlock(&dentry->d_lock);
+
+ /* Do we still want what we've got? */
+ if (want == got)
+ return got;
+
+ ceph_put_cap_refs(ci, got);
+ return 0;
+}
+
/*
* rmdir and unlink are differ only by the metadata op code
*/
@@ -1045,6 +1117,7 @@ static int ceph_unlink(struct inode *dir, struct dentry *dentry)
struct ceph_mds_client *mdsc = fsc->mdsc;
struct inode *inode = d_inode(dentry);
struct ceph_mds_request *req;
+ bool try_async = ceph_test_mount_opt(fsc, ASYNC_DIROPS);
int err = -EROFS;
int op;
@@ -1059,6 +1132,7 @@ static int ceph_unlink(struct inode *dir, struct dentry *dentry)
CEPH_MDS_OP_RMDIR : CEPH_MDS_OP_UNLINK;
} else
goto out;
+retry:
req = ceph_mdsc_create_request(mdsc, op, USE_AUTH_MDS);
if (IS_ERR(req)) {
err = PTR_ERR(req);
@@ -1067,13 +1141,39 @@ static int ceph_unlink(struct inode *dir, struct dentry *dentry)
req->r_dentry = dget(dentry);
req->r_num_caps = 2;
req->r_parent = dir;
- set_bit(CEPH_MDS_R_PARENT_LOCKED, &req->r_req_flags);
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 (try_async && op == CEPH_MDS_OP_UNLINK &&
+ (req->r_dir_caps = get_caps_for_async_unlink(dir, dentry))) {
+ dout("async unlink on %lu/%.*s caps=%s", dir->i_ino,
+ dentry->d_name.len, dentry->d_name.name,
+ ceph_cap_string(req->r_dir_caps));
+ set_bit(CEPH_MDS_R_ASYNC, &req->r_req_flags);
+ 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 if (err == -EJUKEBOX) {
+ try_async = false;
+ ceph_mdsc_put_request(req);
+ goto retry;
+ }
+ } else {
+ set_bit(CEPH_MDS_R_PARENT_LOCKED, &req->r_req_flags);
+ 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;