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authorLinus Torvalds <torvalds@linux-foundation.org>2019-07-10 19:21:38 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2019-07-10 19:21:38 -0700
commit988052f47adc5c3b0b004180b59bb3761d91b752 (patch)
tree044dbcb77fa966b01ad1a4c9b211dccaa62b29a0
parent028db3e290f15ac509084c0fc3b9d021f668f877 (diff)
parent387e3746d01c34457d6a73688acd90428725070b (diff)
Merge tag 'locks-v5.3-1' of git://git.kernel.org/pub/scm/linux/kernel/git/jlayton/linux
Pull file locking updates from Jeff Layton: "Just a couple of small lease-related patches this cycle. One from Ira to add a new tracepoint that fires during lease conflict checks, and another patch from Amir to reduce false positives when checking for lease conflicts" * tag 'locks-v5.3-1' of git://git.kernel.org/pub/scm/linux/kernel/git/jlayton/linux: locks: eliminate false positive conflicts for write lease locks: Add trace_leases_conflict
-rw-r--r--fs/locks.c62
-rw-r--r--include/linux/fs.h4
-rw-r--r--include/trace/events/filelock.h35
3 files changed, 79 insertions, 22 deletions
diff --git a/fs/locks.c b/fs/locks.c
index ec1e4a5df629..de87a3231789 100644
--- a/fs/locks.c
+++ b/fs/locks.c
@@ -1534,11 +1534,21 @@ static void time_out_leases(struct inode *inode, struct list_head *dispose)
static bool leases_conflict(struct file_lock *lease, struct file_lock *breaker)
{
- if ((breaker->fl_flags & FL_LAYOUT) != (lease->fl_flags & FL_LAYOUT))
- return false;
- if ((breaker->fl_flags & FL_DELEG) && (lease->fl_flags & FL_LEASE))
- return false;
- return locks_conflict(breaker, lease);
+ bool rc;
+
+ if ((breaker->fl_flags & FL_LAYOUT) != (lease->fl_flags & FL_LAYOUT)) {
+ rc = false;
+ goto trace;
+ }
+ if ((breaker->fl_flags & FL_DELEG) && (lease->fl_flags & FL_LEASE)) {
+ rc = false;
+ goto trace;
+ }
+
+ rc = locks_conflict(breaker, lease);
+trace:
+ trace_leases_conflict(rc, lease, breaker);
+ return rc;
}
static bool
@@ -1753,10 +1763,10 @@ int fcntl_getlease(struct file *filp)
}
/**
- * check_conflicting_open - see if the given dentry points to a file that has
+ * check_conflicting_open - see if the given file points to an inode that has
* an existing open that would conflict with the
* desired lease.
- * @dentry: dentry to check
+ * @filp: file to check
* @arg: type of lease that we're trying to acquire
* @flags: current lock flags
*
@@ -1764,30 +1774,42 @@ int fcntl_getlease(struct file *filp)
* conflict with the lease we're trying to set.
*/
static int
-check_conflicting_open(const struct dentry *dentry, const long arg, int flags)
+check_conflicting_open(struct file *filp, const long arg, int flags)
{
- int ret = 0;
- struct inode *inode = dentry->d_inode;
+ struct inode *inode = locks_inode(filp);
+ int self_wcount = 0, self_rcount = 0;
if (flags & FL_LAYOUT)
return 0;
- if ((arg == F_RDLCK) && inode_is_open_for_write(inode))
- return -EAGAIN;
+ if (arg == F_RDLCK)
+ return inode_is_open_for_write(inode) ? -EAGAIN : 0;
+ else if (arg != F_WRLCK)
+ return 0;
- if ((arg == F_WRLCK) && ((d_count(dentry) > 1) ||
- (atomic_read(&inode->i_count) > 1)))
- ret = -EAGAIN;
+ /*
+ * 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;
- return ret;
+ 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, long arg, struct file_lock **flp, void **priv)
{
struct file_lock *fl, *my_fl = NULL, *lease;
- struct dentry *dentry = filp->f_path.dentry;
- struct inode *inode = dentry->d_inode;
+ struct inode *inode = locks_inode(filp);
struct file_lock_context *ctx;
bool is_deleg = (*flp)->fl_flags & FL_DELEG;
int error;
@@ -1822,7 +1844,7 @@ generic_add_lease(struct file *filp, long arg, struct file_lock **flp, void **pr
percpu_down_read(&file_rwsem);
spin_lock(&ctx->flc_lock);
time_out_leases(inode, &dispose);
- error = check_conflicting_open(dentry, arg, lease->fl_flags);
+ error = check_conflicting_open(filp, arg, lease->fl_flags);
if (error)
goto out;
@@ -1879,7 +1901,7 @@ generic_add_lease(struct file *filp, long arg, struct file_lock **flp, void **pr
* precedes these checks.
*/
smp_mb();
- error = check_conflicting_open(dentry, arg, lease->fl_flags);
+ error = check_conflicting_open(filp, arg, lease->fl_flags);
if (error) {
locks_unlink_lock_ctx(lease);
goto out;
diff --git a/include/linux/fs.h b/include/linux/fs.h
index c564cf3f48d9..4fb399b77327 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -694,7 +694,7 @@ struct inode {
atomic_t i_count;
atomic_t i_dio_count;
atomic_t i_writecount;
-#ifdef CONFIG_IMA
+#if defined(CONFIG_IMA) || defined(CONFIG_FILE_LOCKING)
atomic_t i_readcount; /* struct files open RO */
#endif
union {
@@ -2890,7 +2890,7 @@ static inline bool inode_is_open_for_write(const struct inode *inode)
return atomic_read(&inode->i_writecount) > 0;
}
-#ifdef CONFIG_IMA
+#if defined(CONFIG_IMA) || defined(CONFIG_FILE_LOCKING)
static inline void i_readcount_dec(struct inode *inode)
{
BUG_ON(!atomic_read(&inode->i_readcount));
diff --git a/include/trace/events/filelock.h b/include/trace/events/filelock.h
index fad7befa612d..4b735923f2ff 100644
--- a/include/trace/events/filelock.h
+++ b/include/trace/events/filelock.h
@@ -203,6 +203,41 @@ TRACE_EVENT(generic_add_lease,
show_fl_type(__entry->fl_type))
);
+TRACE_EVENT(leases_conflict,
+ TP_PROTO(bool conflict, struct file_lock *lease, struct file_lock *breaker),
+
+ TP_ARGS(conflict, lease, breaker),
+
+ TP_STRUCT__entry(
+ __field(void *, lease)
+ __field(void *, breaker)
+ __field(unsigned int, l_fl_flags)
+ __field(unsigned int, b_fl_flags)
+ __field(unsigned char, l_fl_type)
+ __field(unsigned char, b_fl_type)
+ __field(bool, conflict)
+ ),
+
+ TP_fast_assign(
+ __entry->lease = lease;
+ __entry->l_fl_flags = lease->fl_flags;
+ __entry->l_fl_type = lease->fl_type;
+ __entry->breaker = breaker;
+ __entry->b_fl_flags = breaker->fl_flags;
+ __entry->b_fl_type = breaker->fl_type;
+ __entry->conflict = conflict;
+ ),
+
+ TP_printk("conflict %d: lease=0x%p fl_flags=%s fl_type=%s; breaker=0x%p fl_flags=%s fl_type=%s",
+ __entry->conflict,
+ __entry->lease,
+ show_fl_flags(__entry->l_fl_flags),
+ show_fl_type(__entry->l_fl_type),
+ __entry->breaker,
+ show_fl_flags(__entry->b_fl_flags),
+ show_fl_type(__entry->b_fl_type))
+);
+
#endif /* _TRACE_FILELOCK_H */
/* This part must be outside protection */