From 7d8cb26d7dcb911f110b7762bd5941e8f009d6c3 Mon Sep 17 00:00:00 2001 From: Sage Weil Date: Tue, 24 Aug 2010 08:44:16 -0700 Subject: [PATCH] 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: Sage Weil --- fs/ceph/addr.c | 4 ++-- fs/ceph/caps.c | 20 +++++++++++++++++--- fs/ceph/snap.c | 6 +++++- fs/ceph/super.h | 3 ++- 4 files changed, 26 insertions(+), 7 deletions(-) diff --git a/fs/ceph/addr.c b/fs/ceph/addr.c index 420d46974ec8..4cfce1ee31fa 100644 --- a/fs/ceph/addr.c +++ b/fs/ceph/addr.c @@ -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); diff --git a/fs/ceph/caps.c b/fs/ceph/caps.c index ba5bbf318fe1..a2069b6680ae 100644 --- a/fs/ceph/caps.c +++ b/fs/ceph/caps.c @@ -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)); } diff --git a/fs/ceph/snap.c b/fs/ceph/snap.c index 6bdbf3ae7082..4868b9dcac5a 100644 --- a/fs/ceph/snap.c +++ b/fs/ceph/snap.c @@ -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) { diff --git a/fs/ceph/super.h b/fs/ceph/super.h index b33929d8f287..c33897ae5725 100644 --- a/fs/ceph/super.h +++ b/fs/ceph/super.h @@ -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 */ -- 2.20.1