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locks: convert lease handling to file_lock_context

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Signed-off-by: Jeff Layton <jlayton@primarydata.com>
Acked-by: Christoph Hellwig <hch@lst.de>
This commit is contained in:
Jeff Layton 2015-01-16 15:05:55 -05:00 committed by Jeff Layton
parent bd61e0a9c8
commit 8634b51f6c
2 changed files with 104 additions and 157 deletions
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256
fs/locks.c
View File

@ -216,6 +216,7 @@ locks_get_lock_context(struct inode *inode)
INIT_LIST_HEAD(&new->flc_flock);
INIT_LIST_HEAD(&new->flc_posix);
INIT_LIST_HEAD(&new->flc_lease);
/*
* Assign the pointer if it's not already assigned. If it is, then
@ -240,6 +241,7 @@ locks_free_lock_context(struct file_lock_context *ctx)
if (ctx) {
WARN_ON_ONCE(!list_empty(&ctx->flc_flock));
WARN_ON_ONCE(!list_empty(&ctx->flc_posix));
WARN_ON_ONCE(!list_empty(&ctx->flc_lease));
kmem_cache_free(flctx_cache, ctx);
}
}
@ -677,22 +679,6 @@ static void locks_wake_up_blocks(struct file_lock *blocker)
spin_unlock(&blocked_lock_lock);
}
/* Insert file lock fl into an inode's lock list at the position indicated
* by pos. At the same time add the lock to the global file lock list.
*
* Must be called with the i_lock held!
*/
static void locks_insert_lock(struct file_lock **pos, struct file_lock *fl)
{
fl->fl_nspid = get_pid(task_tgid(current));
/* insert into file's list */
fl->fl_next = *pos;
*pos = fl;
locks_insert_global_locks(fl);
}
static void
locks_insert_lock_ctx(struct file_lock *fl, struct list_head *before)
{
@ -701,61 +687,26 @@ locks_insert_lock_ctx(struct file_lock *fl, struct list_head *before)
locks_insert_global_locks(fl);
}
/**
* locks_delete_lock - Delete a lock and then free it.
* @thisfl_p: pointer that points to the fl_next field of the previous
* inode->i_flock list entry
*
* Unlink a lock from all lists and free the namespace reference, but don't
* free it yet. Wake up processes that are blocked waiting for this lock and
* notify the FS that the lock has been cleared.
*
* Must be called with the i_lock held!
*/
static void locks_unlink_lock(struct file_lock **thisfl_p)
static void
locks_unlink_lock_ctx(struct file_lock *fl)
{
struct file_lock *fl = *thisfl_p;
locks_delete_global_locks(fl);
*thisfl_p = fl->fl_next;
fl->fl_next = NULL;
list_del_init(&fl->fl_list);
if (fl->fl_nspid) {
put_pid(fl->fl_nspid);
fl->fl_nspid = NULL;
}
locks_wake_up_blocks(fl);
}
/*
* Unlink a lock from all lists and free it.
*
* Must be called with i_lock held!
*/
static void locks_delete_lock(struct file_lock **thisfl_p,
struct list_head *dispose)
{
struct file_lock *fl = *thisfl_p;
locks_unlink_lock(thisfl_p);
if (dispose)
list_add(&fl->fl_list, dispose);
else
locks_free_lock(fl);
}
static void
locks_delete_lock_ctx(struct file_lock *fl, struct list_head *dispose)
{
locks_delete_global_locks(fl);
if (fl->fl_nspid) {
put_pid(fl->fl_nspid);
fl->fl_nspid = NULL;
}
locks_wake_up_blocks(fl);
list_move(&fl->fl_list, dispose);
locks_unlink_lock_ctx(fl);
if (dispose)
list_add(&fl->fl_list, dispose);
else
locks_free_lock(fl);
}
/* Determine if lock sys_fl blocks lock caller_fl. Common functionality
@ -1376,7 +1327,7 @@ int lease_modify(struct file_lock **before, int arg, struct list_head *dispose)
printk(KERN_ERR "locks_delete_lock: fasync == %p\n", fl->fl_fasync);
fl->fl_fasync = NULL;
}
locks_delete_lock(before, dispose);
locks_delete_lock_ctx(fl, dispose);
}
return 0;
}
@ -1392,20 +1343,17 @@ static bool past_time(unsigned long then)
static void time_out_leases(struct inode *inode, struct list_head *dispose)
{
struct file_lock **before;
struct file_lock *fl;
struct file_lock_context *ctx = inode->i_flctx;
struct file_lock *fl, *tmp;
lockdep_assert_held(&inode->i_lock);
before = &inode->i_flock;
while ((fl = *before) && IS_LEASE(fl) && lease_breaking(fl)) {
list_for_each_entry_safe(fl, tmp, &ctx->flc_lease, fl_list) {
trace_time_out_leases(inode, fl);
if (past_time(fl->fl_downgrade_time))
lease_modify(before, F_RDLCK, dispose);
lease_modify(&fl, F_RDLCK, dispose);
if (past_time(fl->fl_break_time))
lease_modify(before, F_UNLCK, dispose);
if (fl == *before) /* lease_modify may have freed fl */
before = &fl->fl_next;
lease_modify(&fl, F_UNLCK, dispose);
}
}
@ -1419,11 +1367,12 @@ static bool leases_conflict(struct file_lock *lease, struct file_lock *breaker)
static bool
any_leases_conflict(struct inode *inode, struct file_lock *breaker)
{
struct file_lock_context *ctx = inode->i_flctx;
struct file_lock *fl;
lockdep_assert_held(&inode->i_lock);
for (fl = inode->i_flock ; fl && IS_LEASE(fl); fl = fl->fl_next) {
list_for_each_entry(fl, &ctx->flc_lease, fl_list) {
if (leases_conflict(fl, breaker))
return true;
}
@ -1447,7 +1396,8 @@ int __break_lease(struct inode *inode, unsigned int mode, unsigned int type)
{
int error = 0;
struct file_lock *new_fl;
struct file_lock *fl, **before;
struct file_lock_context *ctx = inode->i_flctx;
struct file_lock *fl;
unsigned long break_time;
int want_write = (mode & O_ACCMODE) != O_RDONLY;
LIST_HEAD(dispose);
@ -1457,6 +1407,12 @@ int __break_lease(struct inode *inode, unsigned int mode, unsigned int type)
return PTR_ERR(new_fl);
new_fl->fl_flags = type;
/* typically we will check that ctx is non-NULL before calling */
if (!ctx) {
WARN_ON_ONCE(1);
return error;
}
spin_lock(&inode->i_lock);
time_out_leases(inode, &dispose);
@ -1471,9 +1427,7 @@ int __break_lease(struct inode *inode, unsigned int mode, unsigned int type)
break_time++; /* so that 0 means no break time */
}
for (before = &inode->i_flock;
((fl = *before) != NULL) && IS_LEASE(fl);
before = &fl->fl_next) {
list_for_each_entry(fl, &ctx->flc_lease, fl_list) {
if (!leases_conflict(fl, new_fl))
continue;
if (want_write) {
@ -1482,17 +1436,16 @@ int __break_lease(struct inode *inode, unsigned int mode, unsigned int type)
fl->fl_flags |= FL_UNLOCK_PENDING;
fl->fl_break_time = break_time;
} else {
if (lease_breaking(inode->i_flock))
if (lease_breaking(fl))
continue;
fl->fl_flags |= FL_DOWNGRADE_PENDING;
fl->fl_downgrade_time = break_time;
}
if (fl->fl_lmops->lm_break(fl))
locks_delete_lock(before, &dispose);
locks_delete_lock_ctx(fl, &dispose);
}
fl = inode->i_flock;
if (!fl || !IS_LEASE(fl))
if (list_empty(&ctx->flc_lease))
goto out;
if (mode & O_NONBLOCK) {
@ -1502,12 +1455,13 @@ int __break_lease(struct inode *inode, unsigned int mode, unsigned int type)
}
restart:
break_time = inode->i_flock->fl_break_time;
fl = list_first_entry(&ctx->flc_lease, struct file_lock, fl_list);
break_time = fl->fl_break_time;
if (break_time != 0)
break_time -= jiffies;
if (break_time == 0)
break_time++;
locks_insert_block(inode->i_flock, new_fl);
locks_insert_block(fl, new_fl);
trace_break_lease_block(inode, new_fl);
spin_unlock(&inode->i_lock);
locks_dispose_list(&dispose);
@ -1525,10 +1479,8 @@ restart:
time_out_leases(inode, &dispose);
if (any_leases_conflict(inode, new_fl))
goto restart;
error = 0;
}
out:
spin_unlock(&inode->i_lock);
locks_dispose_list(&dispose);
@ -1550,13 +1502,17 @@ EXPORT_SYMBOL(__break_lease);
void lease_get_mtime(struct inode *inode, struct timespec *time)
{
bool has_lease = false;
struct file_lock *flock;
struct file_lock_context *ctx = inode->i_flctx;
struct file_lock *fl;
if (inode->i_flock) {
if (ctx && !list_empty_careful(&ctx->flc_lease)) {
spin_lock(&inode->i_lock);
flock = inode->i_flock;
if (flock && IS_LEASE(flock) && (flock->fl_type == F_WRLCK))
has_lease = true;
if (!list_empty(&ctx->flc_lease)) {
fl = list_first_entry(&ctx->flc_lease,
struct file_lock, fl_list);
if (fl->fl_type == F_WRLCK)
has_lease = true;
}
spin_unlock(&inode->i_lock);
}
@ -1595,20 +1551,22 @@ int fcntl_getlease(struct file *filp)
{
struct file_lock *fl;
struct inode *inode = file_inode(filp);
struct file_lock_context *ctx = inode->i_flctx;
int type = F_UNLCK;
LIST_HEAD(dispose);
spin_lock(&inode->i_lock);
time_out_leases(file_inode(filp), &dispose);
for (fl = file_inode(filp)->i_flock; fl && IS_LEASE(fl);
fl = fl->fl_next) {
if (fl->fl_file == filp) {
if (ctx && !list_empty_careful(&ctx->flc_lease)) {
spin_lock(&inode->i_lock);
time_out_leases(file_inode(filp), &dispose);
list_for_each_entry(fl, &ctx->flc_lease, fl_list) {
if (fl->fl_file != filp)
continue;
type = target_leasetype(fl);
break;
}
spin_unlock(&inode->i_lock);
locks_dispose_list(&dispose);
}
spin_unlock(&inode->i_lock);
locks_dispose_list(&dispose);
return type;
}
@ -1641,9 +1599,10 @@ check_conflicting_open(const struct dentry *dentry, const long arg)
static int
generic_add_lease(struct file *filp, long arg, struct file_lock **flp, void **priv)
{
struct file_lock *fl, **before, **my_before = NULL, *lease;
struct file_lock *fl, *my_fl = NULL, *lease;
struct dentry *dentry = filp->f_path.dentry;
struct inode *inode = dentry->d_inode;
struct file_lock_context *ctx;
bool is_deleg = (*flp)->fl_flags & FL_DELEG;
int error;
LIST_HEAD(dispose);
@ -1651,6 +1610,10 @@ generic_add_lease(struct file *filp, long arg, struct file_lock **flp, void **pr
lease = *flp;
trace_generic_add_lease(inode, lease);
ctx = locks_get_lock_context(inode);
if (!ctx)
return -ENOMEM;
/*
* In the delegation case we need mutual exclusion with
* a number of operations that take the i_mutex. We trylock
@ -1684,13 +1647,12 @@ generic_add_lease(struct file *filp, long arg, struct file_lock **flp, void **pr
* except for this filp.
*/
error = -EAGAIN;
for (before = &inode->i_flock;
((fl = *before) != NULL) && IS_LEASE(fl);
before = &fl->fl_next) {
list_for_each_entry(fl, &ctx->flc_lease, fl_list) {
if (fl->fl_file == filp) {
my_before = before;
my_fl = fl;
continue;
}
/*
* No exclusive leases if someone else has a lease on
* this file:
@ -1705,9 +1667,8 @@ generic_add_lease(struct file *filp, long arg, struct file_lock **flp, void **pr
goto out;
}
if (my_before != NULL) {
lease = *my_before;
error = lease->fl_lmops->lm_change(my_before, arg, &dispose);
if (my_fl != NULL) {
error = lease->fl_lmops->lm_change(&my_fl, arg, &dispose);
if (error)
goto out;
goto out_setup;
@ -1717,7 +1678,7 @@ generic_add_lease(struct file *filp, long arg, struct file_lock **flp, void **pr
if (!leases_enable)
goto out;
locks_insert_lock(before, lease);
locks_insert_lock_ctx(lease, &ctx->flc_lease);
/*
* The check in break_lease() is lockless. It's possible for another
* open to race in after we did the earlier check for a conflicting
@ -1729,8 +1690,10 @@ generic_add_lease(struct file *filp, long arg, struct file_lock **flp, void **pr
*/
smp_mb();
error = check_conflicting_open(dentry, arg);
if (error)
goto out_unlink;
if (error) {
locks_unlink_lock_ctx(lease);
goto out;
}
out_setup:
if (lease->fl_lmops->lm_setup)
@ -1740,33 +1703,35 @@ out:
locks_dispose_list(&dispose);
if (is_deleg)
mutex_unlock(&inode->i_mutex);
if (!error && !my_before)
if (!error && !my_fl)
*flp = NULL;
return error;
out_unlink:
locks_unlink_lock(before);
goto out;
}
static int generic_delete_lease(struct file *filp)
{
int error = -EAGAIN;
struct file_lock *fl, **before;
struct file_lock *fl, *victim = NULL;
struct dentry *dentry = filp->f_path.dentry;
struct inode *inode = dentry->d_inode;
struct file_lock_context *ctx = inode->i_flctx;
LIST_HEAD(dispose);
if (!ctx) {
trace_generic_delete_lease(inode, NULL);
return error;
}
spin_lock(&inode->i_lock);
time_out_leases(inode, &dispose);
for (before = &inode->i_flock;
((fl = *before) != NULL) && IS_LEASE(fl);
before = &fl->fl_next) {
if (fl->fl_file == filp)
list_for_each_entry(fl, &ctx->flc_lease, fl_list) {
if (fl->fl_file == filp) {
victim = fl;
break;
}
}
trace_generic_delete_lease(inode, fl);
if (fl && IS_LEASE(fl))
error = fl->fl_lmops->lm_change(before, F_UNLCK, &dispose);
if (victim)
error = fl->fl_lmops->lm_change(&victim, F_UNLCK, &dispose);
spin_unlock(&inode->i_lock);
locks_dispose_list(&dispose);
return error;
@ -2447,56 +2412,37 @@ locks_remove_flock(struct file *filp)
fl.fl_ops->fl_release_private(&fl);
}
static void
locks_remove_lease(struct file *filp)
{
struct inode *inode = file_inode(filp);
struct file_lock_context *ctx = inode->i_flctx;
struct file_lock *fl, *tmp;
LIST_HEAD(dispose);
if (!ctx || list_empty(&ctx->flc_lease))
return;
spin_lock(&inode->i_lock);
list_for_each_entry_safe(fl, tmp, &ctx->flc_lease, fl_list)
lease_modify(&fl, F_UNLCK, &dispose);
spin_unlock(&inode->i_lock);
locks_dispose_list(&dispose);
}
/*
* This function is called on the last close of an open file.
*/
void locks_remove_file(struct file *filp)
{
struct inode * inode = file_inode(filp);
struct file_lock *fl;
struct file_lock **before;
LIST_HEAD(dispose);
/* remove any OFD locks */
locks_remove_posix(filp, filp);
/* remove flock locks */
locks_remove_flock(filp);
if (!inode->i_flock)
return;
spin_lock(&inode->i_lock);
before = &inode->i_flock;
while ((fl = *before) != NULL) {
if (fl->fl_file == filp) {
if (IS_LEASE(fl)) {
lease_modify(before, F_UNLCK, &dispose);
continue;
}
/*
* There's a leftover lock on the list of a type that
* we didn't expect to see. Most likely a classic
* POSIX lock that ended up not getting released
* properly, or that raced onto the list somehow. Log
* some info about it and then just remove it from
* the list.
*/
WARN(1, "leftover lock: dev=%u:%u ino=%lu type=%hhd flags=0x%x start=%lld end=%lld\n",
MAJOR(inode->i_sb->s_dev),
MINOR(inode->i_sb->s_dev), inode->i_ino,
fl->fl_type, fl->fl_flags,
fl->fl_start, fl->fl_end);
locks_delete_lock(before, &dispose);
continue;
}
before = &fl->fl_next;
}
spin_unlock(&inode->i_lock);
locks_dispose_list(&dispose);
/* remove any leases */
locks_remove_lease(filp);
}
/**

5
include/linux/fs.h
View File

@ -969,6 +969,7 @@ struct file_lock {
struct file_lock_context {
struct list_head flc_flock;
struct list_head flc_posix;
struct list_head flc_lease;
};
/* The following constant reflects the upper bound of the file/locking space */
@ -1990,7 +1991,7 @@ static inline int break_lease(struct inode *inode, unsigned int mode)
* end up racing with tasks trying to set a new lease on this file.
*/
smp_mb();
if (inode->i_flock)
if (inode->i_flctx && !list_empty_careful(&inode->i_flctx->flc_lease))
return __break_lease(inode, mode, FL_LEASE);
return 0;
}
@ -2003,7 +2004,7 @@ static inline int break_deleg(struct inode *inode, unsigned int mode)
* end up racing with tasks trying to set a new lease on this file.
*/
smp_mb();
if (inode->i_flock)
if (inode->i_flctx && !list_empty_careful(&inode->i_flctx->flc_lease))
return __break_lease(inode, mode, FL_DELEG);
return 0;
}