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authorChristian Brauner <brauner@kernel.org>2025-12-15 15:20:38 +0100
committerChristian Brauner <brauner@kernel.org>2025-12-15 15:20:38 +0100
commit24835a96f21ebb295d24e265b5466d9e40f12cbd (patch)
treedbe3ed4714f1f175c804370716cca79e4107e32d
parented61378b4dc63efe76cb8c23a36b228043332da3 (diff)
parent12965a190eaea614bb49e22041e8fc0d03d0310f (diff)
downloadvfs.fixes.tar.gz
Merge patch series "filelock: fix conflict detection with userland file delegations"vfs.fixes
Jeff Layton <jlayton@kernel.org> says: This patchset fixes the way that conflicts are detected when userland requests file delegations. The problem is due to a hack that was added long ago which worked up until userland could request a file delegation. This fixes the bug and makes things a bit less hacky. Please consider for v6.19. * patches from https://patch.msgid.link/20251204-dir-deleg-ro-v2-0-22d37f92ce2c@kernel.org: filelock: allow lease_managers to dictate what qualifies as a conflict filelock: add lease_dispose_list() helper Link: https://patch.msgid.link/20251204-dir-deleg-ro-v2-0-22d37f92ce2c@kernel.org Signed-off-by: Christian Brauner <brauner@kernel.org>
Diffstat
-rw-r--r--Documentation/filesystems/locking.rst1
-rw-r--r--fs/locks.c119
-rw-r--r--fs/nfsd/nfs4layouts.c23
-rw-r--r--fs/nfsd/nfs4state.c19
-rw-r--r--include/linux/filelock.h1
5 files changed, 103 insertions, 60 deletions
diff --git a/Documentation/filesystems/locking.rst b/Documentation/filesystems/locking.rst
index 77704fde984574..04c7691e50e01f 100644
--- a/Documentation/filesystems/locking.rst
+++ b/Documentation/filesystems/locking.rst
@@ -416,6 +416,7 @@ lm_change yes no no
lm_breaker_owns_lease: yes no no
lm_lock_expirable yes no no
lm_expire_lock no no yes
+lm_open_conflict yes no no
====================== ============= ================= =========
buffer_head
diff --git a/fs/locks.c b/fs/locks.c
index 9f565802a88cd3..e75c8084d937be 100644
--- a/fs/locks.c
+++ b/fs/locks.c
@@ -369,10 +369,19 @@ locks_dispose_list(struct list_head *dispose)
while (!list_empty(dispose)) {
flc = list_first_entry(dispose, struct file_lock_core, flc_list);
list_del_init(&flc->flc_list);
- if (flc->flc_flags & (FL_LEASE|FL_DELEG|FL_LAYOUT))
- locks_free_lease(file_lease(flc));
- else
- locks_free_lock(file_lock(flc));
+ locks_free_lock(file_lock(flc));
+ }
+}
+
+static void
+lease_dispose_list(struct list_head *dispose)
+{
+ struct file_lock_core *flc;
+
+ while (!list_empty(dispose)) {
+ flc = list_first_entry(dispose, struct file_lock_core, flc_list);
+ list_del_init(&flc->flc_list);
+ locks_free_lease(file_lease(flc));
}
}
@@ -576,10 +585,50 @@ lease_setup(struct file_lease *fl, void **priv)
__f_setown(filp, task_pid(current), PIDTYPE_TGID, 0);
}
+/**
+ * lease_open_conflict - see if the given file points to an inode that has
+ * an existing open that would conflict with the
+ * desired lease.
+ * @filp: file to check
+ * @arg: type of lease that we're trying to acquire
+ *
+ * Check to see if there's an existing open fd on this file that would
+ * conflict with the lease we're trying to set.
+ */
+static int
+lease_open_conflict(struct file *filp, const int arg)
+{
+ struct inode *inode = file_inode(filp);
+ int self_wcount = 0, self_rcount = 0;
+
+ if (arg == F_RDLCK)
+ return inode_is_open_for_write(inode) ? -EAGAIN : 0;
+ else if (arg != F_WRLCK)
+ return 0;
+
+ /*
+ * Make sure that only read/write count is from lease requestor.
+ * Note that this will result in denying write leases when i_writecount
+ * is negative, which is what we want. (We shouldn't grant write leases
+ * on files open for execution.)
+ */
+ if (filp->f_mode & FMODE_WRITE)
+ self_wcount = 1;
+ else if (filp->f_mode & FMODE_READ)
+ self_rcount = 1;
+
+ if (atomic_read(&inode->i_writecount) != self_wcount ||
+ atomic_read(&inode->i_readcount) != self_rcount)
+ return -EAGAIN;
+
+ return 0;
+}
+
static const struct lease_manager_operations lease_manager_ops = {
.lm_break = lease_break_callback,
.lm_change = lease_modify,
.lm_setup = lease_setup,
+ .lm_open_conflict = lease_open_conflict,
};
/*
@@ -1620,7 +1669,7 @@ restart:
spin_unlock(&ctx->flc_lock);
percpu_up_read(&file_rwsem);
- locks_dispose_list(&dispose);
+ lease_dispose_list(&dispose);
error = wait_event_interruptible_timeout(new_fl->c.flc_wait,
list_empty(&new_fl->c.flc_blocked_member),
break_time);
@@ -1643,7 +1692,7 @@ restart:
out:
spin_unlock(&ctx->flc_lock);
percpu_up_read(&file_rwsem);
- locks_dispose_list(&dispose);
+ lease_dispose_list(&dispose);
free_lock:
locks_free_lease(new_fl);
return error;
@@ -1727,7 +1776,7 @@ static int __fcntl_getlease(struct file *filp, unsigned int flavor)
spin_unlock(&ctx->flc_lock);
percpu_up_read(&file_rwsem);
- locks_dispose_list(&dispose);
+ lease_dispose_list(&dispose);
}
return type;
}
@@ -1745,52 +1794,6 @@ int fcntl_getdeleg(struct file *filp, struct delegation *deleg)
return 0;
}
-/**
- * check_conflicting_open - see if the given file points to an inode that has
- * an existing open that would conflict with the
- * desired lease.
- * @filp: file to check
- * @arg: type of lease that we're trying to acquire
- * @flags: current lock flags
- *
- * Check to see if there's an existing open fd on this file that would
- * conflict with the lease we're trying to set.
- */
-static int
-check_conflicting_open(struct file *filp, const int arg, int flags)
-{
- struct inode *inode = file_inode(filp);
- int self_wcount = 0, self_rcount = 0;
-
- if (flags & FL_LAYOUT)
- return 0;
- if (flags & FL_DELEG)
- /* We leave these checks to the caller */
- return 0;
-
- if (arg == F_RDLCK)
- return inode_is_open_for_write(inode) ? -EAGAIN : 0;
- else if (arg != F_WRLCK)
- return 0;
-
- /*
- * Make sure that only read/write count is from lease requestor.
- * Note that this will result in denying write leases when i_writecount
- * is negative, which is what we want. (We shouldn't grant write leases
- * on files open for execution.)
- */
- if (filp->f_mode & FMODE_WRITE)
- self_wcount = 1;
- else if (filp->f_mode & FMODE_READ)
- self_rcount = 1;
-
- if (atomic_read(&inode->i_writecount) != self_wcount ||
- atomic_read(&inode->i_readcount) != self_rcount)
- return -EAGAIN;
-
- return 0;
-}
-
static int
generic_add_lease(struct file *filp, int arg, struct file_lease **flp, void **priv)
{
@@ -1827,7 +1830,7 @@ generic_add_lease(struct file *filp, int arg, struct file_lease **flp, void **pr
percpu_down_read(&file_rwsem);
spin_lock(&ctx->flc_lock);
time_out_leases(inode, &dispose);
- error = check_conflicting_open(filp, arg, lease->c.flc_flags);
+ error = lease->fl_lmops->lm_open_conflict(filp, arg);
if (error)
goto out;
@@ -1884,7 +1887,7 @@ generic_add_lease(struct file *filp, int arg, struct file_lease **flp, void **pr
* precedes these checks.
*/
smp_mb();
- error = check_conflicting_open(filp, arg, lease->c.flc_flags);
+ error = lease->fl_lmops->lm_open_conflict(filp, arg);
if (error) {
locks_unlink_lock_ctx(&lease->c);
goto out;
@@ -1896,7 +1899,7 @@ out_setup:
out:
spin_unlock(&ctx->flc_lock);
percpu_up_read(&file_rwsem);
- locks_dispose_list(&dispose);
+ lease_dispose_list(&dispose);
if (is_deleg)
inode_unlock(inode);
if (!error && !my_fl)
@@ -1932,7 +1935,7 @@ static int generic_delete_lease(struct file *filp, void *owner)
error = fl->fl_lmops->lm_change(victim, F_UNLCK, &dispose);
spin_unlock(&ctx->flc_lock);
percpu_up_read(&file_rwsem);
- locks_dispose_list(&dispose);
+ lease_dispose_list(&dispose);
return error;
}
@@ -2727,7 +2730,7 @@ locks_remove_lease(struct file *filp, struct file_lock_context *ctx)
spin_unlock(&ctx->flc_lock);
percpu_up_read(&file_rwsem);
- locks_dispose_list(&dispose);
+ lease_dispose_list(&dispose);
}
/*
diff --git a/fs/nfsd/nfs4layouts.c b/fs/nfsd/nfs4layouts.c
index 683bd1130afe29..ad7af8cfcf1f90 100644
--- a/fs/nfsd/nfs4layouts.c
+++ b/fs/nfsd/nfs4layouts.c
@@ -764,9 +764,28 @@ nfsd4_layout_lm_change(struct file_lease *onlist, int arg,
return lease_modify(onlist, arg, dispose);
}
+/**
+ * nfsd4_layout_lm_open_conflict - see if the given file points to an inode that has
+ * an existing open that would conflict with the
+ * desired lease.
+ * @filp: file to check
+ * @arg: type of lease that we're trying to acquire
+ *
+ * The kernel will call into this operation to determine whether there
+ * are conflicting opens that may prevent the layout from being granted.
+ * For nfsd, that check is done at a higher level, so this trivially
+ * returns 0.
+ */
+static int
+nfsd4_layout_lm_open_conflict(struct file *filp, int arg)
+{
+ return 0;
+}
+
static const struct lease_manager_operations nfsd4_layouts_lm_ops = {
- .lm_break = nfsd4_layout_lm_break,
- .lm_change = nfsd4_layout_lm_change,
+ .lm_break = nfsd4_layout_lm_break,
+ .lm_change = nfsd4_layout_lm_change,
+ .lm_open_conflict = nfsd4_layout_lm_open_conflict,
};
int
diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index 808c24fb5c9a0b..19d6d6db107ff6 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -5552,10 +5552,29 @@ nfsd_change_deleg_cb(struct file_lease *onlist, int arg,
return -EAGAIN;
}
+/**
+ * nfsd4_deleg_lm_open_conflict - see if the given file points to an inode that has
+ * an existing open that would conflict with the
+ * desired lease.
+ * @filp: file to check
+ * @arg: type of lease that we're trying to acquire
+ *
+ * The kernel will call into this operation to determine whether there
+ * are conflicting opens that may prevent the deleg from being granted.
+ * For nfsd, that check is done at a higher level, so this trivially
+ * returns 0.
+ */
+static int
+nfsd4_deleg_lm_open_conflict(struct file *filp, int arg)
+{
+ return 0;
+}
+
static const struct lease_manager_operations nfsd_lease_mng_ops = {
.lm_breaker_owns_lease = nfsd_breaker_owns_lease,
.lm_break = nfsd_break_deleg_cb,
.lm_change = nfsd_change_deleg_cb,
+ .lm_open_conflict = nfsd4_deleg_lm_open_conflict,
};
static __be32 nfsd4_check_seqid(struct nfsd4_compound_state *cstate, struct nfs4_stateowner *so, u32 seqid)
diff --git a/include/linux/filelock.h b/include/linux/filelock.h
index 54b824c0529926..2f5e5588ee0733 100644
--- a/include/linux/filelock.h
+++ b/include/linux/filelock.h
@@ -49,6 +49,7 @@ struct lease_manager_operations {
int (*lm_change)(struct file_lease *, int, struct list_head *);
void (*lm_setup)(struct file_lease *, void **);
bool (*lm_breaker_owns_lease)(struct file_lease *);
+ int (*lm_open_conflict)(struct file *, int);
};
struct lock_manager {
generated by cgit 1.2.3-korg (git 2.43.0) at 2025-12-23 23:23:52 +0000