[PATCH v2 20/41] filelock: convert __locks_insert_block, conflict and deadlock checks to use file_lock_core

Jeff Layton
2024-01-25T10:44:31Z

Have both __locks_insert_block and the deadlock and conflict checking
functions take a struct file_lock_core pointer instead of a struct
file_lock one. Also, change posix_locks_deadlock to return bool.

Signed-off-by: Jeff Layton <jlayton@kernel.org>
---
fs/locks.c | 134 +++++++++++++++++++++++++++++++++----------------------------
1 file changed, 73 insertions(+), 61 deletions(-)

diff --git a/fs/locks.c b/fs/locks.c
index fb113103dc1b..a86841fc8220 100644
--- a/fs/locks.c
+++ b/fs/locks.c
@@ -757,39 +757,41 @@ EXPORT_SYMBOL(locks_delete_block);
* waiters, and add beneath any waiter that blocks the new waiter.
* Thus wakeups don't happen until needed.
*/
-static void __locks_insert_block(struct file_lock *blocker,
- struct file_lock *waiter,
- bool conflict(struct file_lock *,
- struct file_lock *))
+static void __locks_insert_block(struct file_lock *blocker_fl,
+ struct file_lock *waiter_fl,
+ bool conflict(struct file_lock_core *,
+ struct file_lock_core *))
{
- struct file_lock *fl;
- BUG_ON(!list_empty(&waiter->fl_core.flc_blocked_member));
+ struct file_lock_core *blocker = &blocker_fl->fl_core;
+ struct file_lock_core *waiter = &waiter_fl->fl_core;
+ struct file_lock_core *flc;

+ BUG_ON(!list_empty(&waiter->flc_blocked_member));
new_blocker:
- list_for_each_entry(fl, &blocker->fl_core.flc_blocked_requests,
- fl_core.flc_blocked_member)
- if (conflict(fl, waiter)) {
- blocker = fl;
+ list_for_each_entry(flc, &blocker->flc_blocked_requests, flc_blocked_member)
+ if (conflict(flc, waiter)) {
+ blocker = flc;
goto new_blocker;
}
- waiter->fl_core.flc_blocker = blocker;
- list_add_tail(&waiter->fl_core.flc_blocked_member,
- &blocker->fl_core.flc_blocked_requests);
- if ((blocker->fl_core.flc_flags & (FL_POSIX|FL_OFDLCK)) == FL_POSIX)
- locks_insert_global_blocked(&waiter->fl_core);
+ waiter->flc_blocker = file_lock(blocker);
+ list_add_tail(&waiter->flc_blocked_member,
+ &blocker->flc_blocked_requests);

- /* The requests in waiter->fl_blocked are known to conflict with
+ if ((blocker->flc_flags & (FL_POSIX|FL_OFDLCK)) == (FL_POSIX|FL_OFDLCK))
+ locks_insert_global_blocked(waiter);
+
+ /* The requests in waiter->flc_blocked are known to conflict with
* waiter, but might not conflict with blocker, or the requests
* and lock which block it. So they all need to be woken.
*/
- __locks_wake_up_blocks(&waiter->fl_core);
+ __locks_wake_up_blocks(waiter);
}

/* Must be called with flc_lock held. */
static void locks_insert_block(struct file_lock *blocker,
struct file_lock *waiter,
- bool conflict(struct file_lock *,
- struct file_lock *))
+ bool conflict(struct file_lock_core *,
+ struct file_lock_core *))
{
spin_lock(&blocked_lock_lock);
__locks_insert_block(blocker, waiter, conflict);
@@ -846,12 +848,12 @@ locks_delete_lock_ctx(struct file_lock *fl, struct list_head *dispose)
/* Determine if lock sys_fl blocks lock caller_fl. Common functionality
* checks for shared/exclusive status of overlapping locks.
*/
-static bool locks_conflict(struct file_lock *caller_fl,
- struct file_lock *sys_fl)
+static bool locks_conflict(struct file_lock_core *caller_fl,
+ struct file_lock_core *sys_fl)
{
- if (sys_fl->fl_core.flc_type == F_WRLCK)
+ if (sys_fl->flc_type == F_WRLCK)
return true;
- if (caller_fl->fl_core.flc_type == F_WRLCK)
+ if (caller_fl->flc_type == F_WRLCK)
return true;
return false;
}
@@ -859,20 +861,23 @@ static bool locks_conflict(struct file_lock *caller_fl,
/* Determine if lock sys_fl blocks lock caller_fl. POSIX specific
* checking before calling the locks_conflict().
*/
-static bool posix_locks_conflict(struct file_lock *caller_fl,
- struct file_lock *sys_fl)
+static bool posix_locks_conflict(struct file_lock_core *caller_flc,
+ struct file_lock_core *sys_flc)
{
+ struct file_lock *caller_fl = file_lock(caller_flc);
+ struct file_lock *sys_fl = file_lock(sys_flc);
+
/* POSIX locks owned by the same process do not conflict with
* each other.
*/
- if (posix_same_owner(&caller_fl->fl_core, &sys_fl->fl_core))
+ if (posix_same_owner(caller_flc, sys_flc))
return false;

/* Check whether they overlap */
if (!locks_overlap(caller_fl, sys_fl))
return false;

- return locks_conflict(caller_fl, sys_fl);
+ return locks_conflict(caller_flc, sys_flc);
}

/* Determine if lock sys_fl blocks lock caller_fl. Used on xx_GETLK
@@ -881,28 +886,31 @@ static bool posix_locks_conflict(struct file_lock *caller_fl,
static bool posix_test_locks_conflict(struct file_lock *caller_fl,
struct file_lock *sys_fl)
{
+ struct file_lock_core *caller = &caller_fl->fl_core;
+ struct file_lock_core *sys = &sys_fl->fl_core;
+
/* F_UNLCK checks any locks on the same fd. */
- if (caller_fl->fl_core.flc_type == F_UNLCK) {
- if (!posix_same_owner(&caller_fl->fl_core, &sys_fl->fl_core))
+ if (caller->flc_type == F_UNLCK) {
+ if (!posix_same_owner(caller, sys))
return false;
return locks_overlap(caller_fl, sys_fl);
}
- return posix_locks_conflict(caller_fl, sys_fl);
+ return posix_locks_conflict(caller, sys);
}

/* Determine if lock sys_fl blocks lock caller_fl. FLOCK specific
* checking before calling the locks_conflict().
*/
-static bool flock_locks_conflict(struct file_lock *caller_fl,
- struct file_lock *sys_fl)
+static bool flock_locks_conflict(struct file_lock_core *caller_flc,
+ struct file_lock_core *sys_flc)
{
/* FLOCK locks referring to the same filp do not conflict with
* each other.
*/
- if (caller_fl->fl_core.flc_file == sys_fl->fl_core.flc_file)
+ if (caller_flc->flc_file == sys_flc->flc_file)
return false;

- return locks_conflict(caller_fl, sys_fl);
+ return locks_conflict(caller_flc, sys_flc);
}

void
@@ -980,25 +988,27 @@ EXPORT_SYMBOL(posix_test_lock);

#define MAX_DEADLK_ITERATIONS 10

-/* Find a lock that the owner of the given block_fl is blocking on. */
-static struct file_lock *what_owner_is_waiting_for(struct file_lock *block_fl)
+/* Find a lock that the owner of the given @blocker is blocking on. */
+static struct file_lock_core *what_owner_is_waiting_for(struct file_lock_core *blocker)
{
- struct file_lock *fl;
+ struct file_lock_core *flc;

- hash_for_each_possible(blocked_hash, fl, fl_core.flc_link, posix_owner_key(&block_fl->fl_core)) {
- if (posix_same_owner(&fl->fl_core, &block_fl->fl_core)) {
- while (fl->fl_core.flc_blocker)
- fl = fl->fl_core.flc_blocker;
- return fl;
+ hash_for_each_possible(blocked_hash, flc, flc_link, posix_owner_key(blocker)) {
+ if (posix_same_owner(flc, blocker)) {
+ while (flc->flc_blocker)
+ flc = &flc->flc_blocker->fl_core;
+ return flc;
}
}
return NULL;
}

/* Must be called with the blocked_lock_lock held! */
-static int posix_locks_deadlock(struct file_lock *caller_fl,
- struct file_lock *block_fl)
+static bool posix_locks_deadlock(struct file_lock *caller_fl,
+ struct file_lock *block_fl)
{
+ struct file_lock_core *caller = &caller_fl->fl_core;
+ struct file_lock_core *blocker = &block_fl->fl_core;
int i = 0;

lockdep_assert_held(&blocked_lock_lock);
@@ -1007,16 +1017,16 @@ static int posix_locks_deadlock(struct file_lock *caller_fl,
* This deadlock detector can't reasonably detect deadlocks with
* FL_OFDLCK locks, since they aren't owned by a process, per-se.
*/
- if (caller_fl->fl_core.flc_flags & FL_OFDLCK)
- return 0;
+ if (caller->flc_flags & FL_OFDLCK)
+ return false;

- while ((block_fl = what_owner_is_waiting_for(block_fl))) {
+ while ((blocker = what_owner_is_waiting_for(blocker))) {
if (i++ > MAX_DEADLK_ITERATIONS)
- return 0;
- if (posix_same_owner(&caller_fl->fl_core, &block_fl->fl_core))
- return 1;
+ return false;
+ if (posix_same_owner(caller, blocker))
+ return true;
}
- return 0;
+ return false;
}

/* Try to create a FLOCK lock on filp. We always insert new FLOCK locks
@@ -1071,7 +1081,7 @@ static int flock_lock_inode(struct inode *inode, struct file_lock *request)

find_conflict:
list_for_each_entry(fl, &ctx->flc_flock, fl_core.flc_list) {
- if (!flock_locks_conflict(request, fl))
+ if (!flock_locks_conflict(&request->fl_core, &fl->fl_core))
continue;
error = -EAGAIN;
if (!(request->fl_core.flc_flags & FL_SLEEP))
@@ -1140,7 +1150,7 @@ static int posix_lock_inode(struct inode *inode, struct file_lock *request,
*/
if (request->fl_core.flc_type != F_UNLCK) {
list_for_each_entry(fl, &ctx->flc_posix, fl_core.flc_list) {
- if (!posix_locks_conflict(request, fl))
+ if (!posix_locks_conflict(&request->fl_core, &fl->fl_core))
continue;
if (fl->fl_lmops && fl->fl_lmops->lm_lock_expirable
&& (*fl->fl_lmops->lm_lock_expirable)(fl)) {
@@ -1442,23 +1452,25 @@ static void time_out_leases(struct inode *inode, struct list_head *dispose)
}
}

-static bool leases_conflict(struct file_lock *lease, struct file_lock *breaker)
+static bool leases_conflict(struct file_lock_core *lc, struct file_lock_core *bc)
{
bool rc;
+ struct file_lock *lease = file_lock(lc);
+ struct file_lock *breaker = file_lock(bc);

if (lease->fl_lmops->lm_breaker_owns_lease
&& lease->fl_lmops->lm_breaker_owns_lease(lease))
return false;
- if ((breaker->fl_core.flc_flags & FL_LAYOUT) != (lease->fl_core.flc_flags & FL_LAYOUT)) {
+ if ((bc->flc_flags & FL_LAYOUT) != (lc->flc_flags & FL_LAYOUT)) {
rc = false;
goto trace;
}
- if ((breaker->fl_core.flc_flags & FL_DELEG) && (lease->fl_core.flc_flags & FL_LEASE)) {
+ if ((bc->flc_flags & FL_DELEG) && (lc->flc_flags & FL_LEASE)) {
rc = false;
goto trace;
}

- rc = locks_conflict(breaker, lease);
+ rc = locks_conflict(bc, lc);
trace:
trace_leases_conflict(rc, lease, breaker);
return rc;
@@ -1468,12 +1480,12 @@ static bool
any_leases_conflict(struct inode *inode, struct file_lock *breaker)
{
struct file_lock_context *ctx = inode->i_flctx;
- struct file_lock *fl;
+ struct file_lock_core *flc;

lockdep_assert_held(&ctx->flc_lock);

- list_for_each_entry(fl, &ctx->flc_lease, fl_core.flc_list) {
- if (leases_conflict(fl, breaker))
+ list_for_each_entry(flc, &ctx->flc_lease, flc_list) {
+ if (leases_conflict(flc, &breaker->fl_core))
return true;
}
return false;
@@ -1529,7 +1541,7 @@ int __break_lease(struct inode *inode, unsigned int mode, unsigned int type)
}

list_for_each_entry_safe(fl, tmp, &ctx->flc_lease, fl_core.flc_list) {
- if (!leases_conflict(fl, new_fl))
+ if (!leases_conflict(&fl->fl_core, &new_fl->fl_core))
continue;
if (want_write) {
if (fl->fl_core.flc_flags & FL_UNLOCK_PENDING)

--
2.43.0