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ceph: fix flush_dirty_caps race with caps migration

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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: Sage Weil <sage@newdream.net>
This commit is contained in:
Sage Weil 2010-03-01 15:16:56 -08:00
parent 7af8f1e4aa
commit e9964c1023
2 changed files with 39 additions and 7 deletions
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45
fs/ceph/caps.c
View file

@ -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,
i_dirty_item);
inode = igrab(&ci->vfs_inode);
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,

1
fs/ceph/super.h
View file

@ -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 */