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Commit e9964c10 authored by Sage Weil's avatar Sage Weil
Browse files

ceph: fix flush_dirty_caps race with caps migration 



The flush_dirty_caps() used to loop over the first entry of the cap_dirty
dirty list on the assumption that after calling ceph_check_caps() it would
be removed from the list.  This isn't true for caps that are being
migrated between MDSs, where we've received the EXPORT but not the IMPORT.

Instead, do a safe list iteration, and pin the next inode on the list via
the CEPH_I_NOFLUSH flag.

Signed-off-by: default avatarSage Weil <sage@newdream.net>
parent 7af8f1e4

fs/ceph/caps.c

+38 −7
Original line number Diff line number Diff line
@@ -1573,6 +1573,11 @@ void ceph_check_caps(struct ceph_inode_info *ci, int flags, 
		}



ack:

		if (ci->i_ceph_flags & CEPH_I_NOFLUSH) {

			dout(" skipping %p I_NOFLUSH set\n", inode);

			continue;

		}



		if (session && session != cap->session) {

			dout("oops, wrong session %p mutex\n", session);

			mutex_unlock(&session->s_mutex);
@@ -1652,6 +1657,10 @@ static int try_flush_caps(struct inode *inode, struct ceph_mds_session *session, 


retry:

	spin_lock(&inode->i_lock);

	if (ci->i_ceph_flags & CEPH_I_NOFLUSH) {

		dout("try_flush_caps skipping %p I_NOFLUSH set\n", inode);

		goto out;

	}

	if (ci->i_dirty_caps && ci->i_auth_cap) {

		struct ceph_cap *cap = ci->i_auth_cap;

		int used = __ceph_caps_used(ci);
@@ -2747,16 +2756,38 @@ void ceph_check_delayed_caps(struct ceph_mds_client *mdsc) 
 */

void ceph_flush_dirty_caps(struct ceph_mds_client *mdsc)

{

	struct ceph_inode_info *ci;

	struct inode *inode;

	struct ceph_inode_info *ci, *nci = NULL;

	struct inode *inode, *ninode = NULL;

	struct list_head *p, *n;



	dout("flush_dirty_caps\n");

	spin_lock(&mdsc->cap_dirty_lock);

	while (!list_empty(&mdsc->cap_dirty)) {

		ci = list_first_entry(&mdsc->cap_dirty,

				      struct ceph_inode_info,

	list_for_each_safe(p, n, &mdsc->cap_dirty) {

		if (nci) {

			ci = nci;

			inode = ninode;

			ci->i_ceph_flags &= ~CEPH_I_NOFLUSH;

			dout("flush_dirty_caps inode %p (was next inode)\n",

			     inode);

		} else {

			ci = list_entry(p, struct ceph_inode_info,

					i_dirty_item);

			inode = igrab(&ci->vfs_inode);

			BUG_ON(!inode);

			dout("flush_dirty_caps inode %p\n", inode);

		}

		if (n != &mdsc->cap_dirty) {

			nci = list_entry(n, struct ceph_inode_info,

					 i_dirty_item);

			ninode = igrab(&nci->vfs_inode);

			BUG_ON(!ninode);

			nci->i_ceph_flags |= CEPH_I_NOFLUSH;

			dout("flush_dirty_caps next inode %p, noflush\n",

			     ninode);

		} else {

			nci = NULL;

			ninode = NULL;

		}

		spin_unlock(&mdsc->cap_dirty_lock);

		if (inode) {

			ceph_check_caps(ci, CHECK_CAPS_NODELAY|CHECK_CAPS_FLUSH,

fs/ceph/super.h

+1 −0
Original line number Diff line number Diff line
@@ -289,6 +289,7 @@ struct ceph_inode_xattrs_info { 
#define CEPH_I_COMPLETE  1  /* we have complete directory cached */

#define CEPH_I_NODELAY   4  /* do not delay cap release */

#define CEPH_I_FLUSH     8  /* do not delay flush of dirty metadata */

#define CEPH_I_NOFLUSH  16  /* do not flush dirty caps */



struct ceph_inode_info {

	struct ceph_vino i_vino;   /* ceph ino + snap */