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authorDavid Howells <dhowells@redhat.com>2019-05-13 18:14:32 +0300
committerDavid Howells <dhowells@redhat.com>2019-05-17 00:23:21 +0300
commitf642404a0436a50912c218009ccc7856d48d784c (patch)
treeddf39d1741f07866333581e66f1abc0e6709d453 /fs/afs/rotate.c
parentc925bd0ac4741badb567f594c41c8cba5e9e9732 (diff)
downloadlinux-f642404a0436a50912c218009ccc7856d48d784c.tar.xz
afs: Make vnode->cb_interest RCU safe
Use RCU-based freeing for afs_cb_interest struct objects and use RCU on vnode->cb_interest. Use that change to allow afs_check_validity() to use read_seqbegin_or_lock() instead of read_seqlock_excl(). This also requires the caller of afs_check_validity() to hold the RCU read lock across the call. Signed-off-by: David Howells <dhowells@redhat.com>
Diffstat (limited to 'fs/afs/rotate.c')
-rw-r--r--fs/afs/rotate.c18
1 files changed, 12 insertions, 6 deletions
diff --git a/fs/afs/rotate.c b/fs/afs/rotate.c
index 52f3a9910f0d..b00c739e0e63 100644
--- a/fs/afs/rotate.c
+++ b/fs/afs/rotate.c
@@ -66,7 +66,8 @@ static bool afs_start_fs_iteration(struct afs_fs_cursor *fc,
fc->untried = (1UL << fc->server_list->nr_servers) - 1;
fc->index = READ_ONCE(fc->server_list->preferred);
- cbi = vnode->cb_interest;
+ cbi = rcu_dereference_protected(vnode->cb_interest,
+ lockdep_is_held(&vnode->io_lock));
if (cbi) {
/* See if the vnode's preferred record is still available */
for (i = 0; i < fc->server_list->nr_servers; i++) {
@@ -87,8 +88,8 @@ static bool afs_start_fs_iteration(struct afs_fs_cursor *fc,
/* Note that the callback promise is effectively broken */
write_seqlock(&vnode->cb_lock);
- ASSERTCMP(cbi, ==, vnode->cb_interest);
- vnode->cb_interest = NULL;
+ ASSERTCMP(cbi, ==, rcu_access_pointer(vnode->cb_interest));
+ rcu_assign_pointer(vnode->cb_interest, NULL);
if (test_and_clear_bit(AFS_VNODE_CB_PROMISED, &vnode->flags))
vnode->cb_break++;
write_sequnlock(&vnode->cb_lock);
@@ -417,7 +418,9 @@ selected_server:
if (error < 0)
goto failed_set_error;
- fc->cbi = afs_get_cb_interest(vnode->cb_interest);
+ fc->cbi = afs_get_cb_interest(
+ rcu_dereference_protected(vnode->cb_interest,
+ lockdep_is_held(&vnode->io_lock)));
read_lock(&server->fs_lock);
alist = rcu_dereference_protected(server->addresses,
@@ -487,12 +490,15 @@ failed:
bool afs_select_current_fileserver(struct afs_fs_cursor *fc)
{
struct afs_vnode *vnode = fc->vnode;
- struct afs_cb_interest *cbi = vnode->cb_interest;
+ struct afs_cb_interest *cbi;
struct afs_addr_list *alist;
int error = fc->ac.error;
_enter("");
+ cbi = rcu_dereference_protected(vnode->cb_interest,
+ lockdep_is_held(&vnode->io_lock));
+
switch (error) {
case SHRT_MAX:
if (!cbi) {
@@ -501,7 +507,7 @@ bool afs_select_current_fileserver(struct afs_fs_cursor *fc)
return false;
}
- fc->cbi = afs_get_cb_interest(vnode->cb_interest);
+ fc->cbi = afs_get_cb_interest(cbi);
read_lock(&cbi->server->fs_lock);
alist = rcu_dereference_protected(cbi->server->addresses,