Commit 7d8cb26d authored by Sage Weil's avatar Sage Weil
Browse files

ceph: maintain i_head_snapc when any caps are dirty, not just for data 



We used to use i_head_snapc to keep track of which snapc the current epoch
of dirty data was dirtied under.  It is used by queue_cap_snap to set up
the cap_snap.  However, since we queue cap snaps for any dirty caps, not
just for dirty file data, we need to keep a valid i_head_snapc anytime
we have dirty|flushing caps.  This fixes a NULL pointer deref in
queue_cap_snap when writing back dirty caps without data (e.g.,
snaptest-authwb.sh).

Signed-off-by: default avatarSage Weil <sage@newdream.net>
parent 07a27e22

fs/ceph/addr.c

+2 −2
Original line number Diff line number Diff line
@@ -87,7 +87,7 @@ static int ceph_set_page_dirty(struct page *page) 


	/* dirty the head */

	spin_lock(&inode->i_lock);

	if (ci->i_wrbuffer_ref_head == 0)

	if (ci->i_head_snapc == NULL)

		ci->i_head_snapc = ceph_get_snap_context(snapc);

	++ci->i_wrbuffer_ref_head;

	if (ci->i_wrbuffer_ref == 0)
@@ -346,7 +346,7 @@ static struct ceph_snap_context *get_oldest_context(struct inode *inode, 
			break;

		}

	}

	if (!snapc && ci->i_head_snapc) {

	if (!snapc && ci->i_wrbuffer_ref_head) {

		snapc = ceph_get_snap_context(ci->i_head_snapc);

		dout(" head snapc %p has %d dirty pages\n",

		     snapc, ci->i_wrbuffer_ref_head);

fs/ceph/caps.c

+17 −3
Original line number Diff line number Diff line
@@ -1143,6 +1143,10 @@ static int __send_cap(struct ceph_mds_client *mdsc, struct ceph_cap *cap, 
		for (i = 0; i < CEPH_CAP_BITS; i++)

			if (flushing & (1 << i))

				ci->i_cap_flush_tid[i] = flush_tid;



		follows = ci->i_head_snapc->seq;

	} else {

		follows = 0;

	}



	keep = cap->implemented;
@@ -1156,7 +1160,6 @@ static int __send_cap(struct ceph_mds_client *mdsc, struct ceph_cap *cap, 
	mtime = inode->i_mtime;

	atime = inode->i_atime;

	time_warp_seq = ci->i_time_warp_seq;

	follows = ci->i_snap_realm->cached_context->seq;

	uid = inode->i_uid;

	gid = inode->i_gid;

	mode = inode->i_mode;
@@ -1332,7 +1335,11 @@ void __ceph_mark_dirty_caps(struct ceph_inode_info *ci, int mask) 
	     ceph_cap_string(was | mask));

	ci->i_dirty_caps |= mask;

	if (was == 0) {

		dout(" inode %p now dirty\n", &ci->vfs_inode);

		if (!ci->i_head_snapc)

			ci->i_head_snapc = ceph_get_snap_context(

				ci->i_snap_realm->cached_context);

		dout(" inode %p now dirty snapc %p\n", &ci->vfs_inode,

			ci->i_head_snapc);

		BUG_ON(!list_empty(&ci->i_dirty_item));

		spin_lock(&mdsc->cap_dirty_lock);

		list_add(&ci->i_dirty_item, &mdsc->cap_dirty);
@@ -2190,7 +2197,9 @@ void ceph_put_wrbuffer_cap_refs(struct ceph_inode_info *ci, int nr, 


	if (ci->i_head_snapc == snapc) {

		ci->i_wrbuffer_ref_head -= nr;

		if (!ci->i_wrbuffer_ref_head) {

		if (ci->i_wrbuffer_ref_head == 0 &&

		    ci->i_dirty_caps == 0 && ci->i_flushing_caps == 0) {

			BUG_ON(!ci->i_head_snapc);

			ceph_put_snap_context(ci->i_head_snapc);

			ci->i_head_snapc = NULL;

		}
@@ -2483,6 +2492,11 @@ static void handle_cap_flush_ack(struct inode *inode, u64 flush_tid, 
			dout(" inode %p now clean\n", inode);

			BUG_ON(!list_empty(&ci->i_dirty_item));

			drop = 1;

			if (ci->i_wrbuffer_ref_head == 0) {

				BUG_ON(!ci->i_head_snapc);

				ceph_put_snap_context(ci->i_head_snapc);

				ci->i_head_snapc = NULL;

			}

		} else {

			BUG_ON(list_empty(&ci->i_dirty_item));

		}

fs/ceph/snap.c

+5 −1
Original line number Diff line number Diff line
@@ -458,6 +458,8 @@ void ceph_queue_cap_snap(struct ceph_inode_info *ci) 
			     CEPH_CAP_FILE_EXCL|CEPH_CAP_FILE_WR))) {

		struct ceph_snap_context *snapc = ci->i_head_snapc;



		dout("queue_cap_snap %p cap_snap %p queuing under %p\n", inode,

		     capsnap, snapc);

		igrab(inode);

		

		atomic_set(&capsnap->nref, 1);
@@ -489,7 +491,9 @@ void ceph_queue_cap_snap(struct ceph_inode_info *ci) 
		capsnap->dirty_pages = ci->i_wrbuffer_ref_head;

		ci->i_wrbuffer_ref_head = 0;

		capsnap->context = snapc;

		ci->i_head_snapc = NULL;

		ci->i_head_snapc =

			ceph_get_snap_context(ci->i_snap_realm->cached_context);

		dout(" new snapc is %p\n", ci->i_head_snapc);

		list_add_tail(&capsnap->ci_item, &ci->i_cap_snaps);



		if (used & CEPH_CAP_FILE_WR) {

fs/ceph/super.h

+2 −1
Original line number Diff line number Diff line
@@ -344,7 +344,8 @@ struct ceph_inode_info { 
	unsigned i_cap_exporting_issued;

	struct ceph_cap_reservation i_cap_migration_resv;

	struct list_head i_cap_snaps;   /* snapped state pending flush to mds */

	struct ceph_snap_context *i_head_snapc;  /* set if wr_buffer_head > 0 */

	struct ceph_snap_context *i_head_snapc;  /* set if wr_buffer_head > 0 or

						    dirty|flushing caps */

	unsigned i_snap_caps;           /* cap bits for snapped files */



	int i_nr_by_mode[CEPH_FILE_MODE_NUM];  /* open file counts */

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