[RFC PATCH 05/12] locks: convert posix locks to file_lock_context

Jeff Layton
2014-09-10T14:29:10Z

fs/locks.c | 119 ++++++++++++++++++++++++++++-------------------------
fs/read_write.c | 2 +-
include/linux/fs.h | 3 +-
3 files changed, 65 insertions(+), 59 deletions(-)

diff --git a/fs/locks.c b/fs/locks.c
index 7f8c2c68a769..750813e708c8 100644
--- a/fs/locks.c
+++ b/fs/locks.c
@@ -157,9 +157,6 @@ static int target_leasetype(struct file_lock *fl)
int leases_enable = 1;
int lease_break_time = 45;

-#define for_each_lock(inode, lockp) \
- for (lockp = &inode->i_flock; *lockp != NULL; lockp = &(*lockp)->fl_next)
-
/*
* The global file_lock_list is only used for displaying /proc/locks, so we
* keep a list on each CPU, with each list protected by its own spinlock via
@@ -221,6 +218,7 @@ locks_get_lock_context(struct inode *inode)
if (likely(!inode->i_flctx)) {
spin_lock_init(&new->flc_lock);
INIT_LIST_HEAD(&new->flc_flock);
+ INIT_LIST_HEAD(&new->flc_posix);
swap(inode->i_flctx, new);
}
spin_unlock(&inode->i_lock);
@@ -235,6 +233,7 @@ 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));
kmem_cache_free(flctx_cache, ctx);
}
}
@@ -803,22 +802,27 @@ void
posix_test_lock(struct file *filp, struct file_lock *fl)
{
struct file_lock *cfl;
+ struct file_lock_context *ctx;
struct inode *inode = file_inode(filp);

- spin_lock(&inode->i_lock);
- for (cfl = file_inode(filp)->i_flock; cfl; cfl = cfl->fl_next) {
- if (!IS_POSIX(cfl))
- continue;
- if (posix_locks_conflict(fl, cfl))
- break;
- }
- if (cfl) {
- locks_copy_conflock(fl, cfl);
- if (cfl->fl_nspid)
- fl->fl_pid = pid_vnr(cfl->fl_nspid);
- } else
+ ctx = inode->i_flctx;
+ if (!ctx) {
fl->fl_type = F_UNLCK;
- spin_unlock(&inode->i_lock);
+ return;
+ }
+
+ spin_lock(&ctx->flc_lock);
+ list_for_each_entry(cfl, &ctx->flc_posix, fl_list) {
+ if (posix_locks_conflict(fl, cfl)) {
+ locks_copy_conflock(fl, cfl);
+ if (cfl->fl_nspid)
+ fl->fl_pid = pid_vnr(cfl->fl_nspid);
+ goto out;
+ }
+ }
+ fl->fl_type = F_UNLCK;
+out:
+ spin_unlock(&ctx->flc_lock);
return;
}
EXPORT_SYMBOL(posix_test_lock);
@@ -977,16 +981,20 @@ out:

static int __posix_lock_file(struct inode *inode, struct file_lock *request, struct file_lock *conflock)
{
- struct file_lock *fl;
+ struct file_lock *fl, *tmp;
struct file_lock *new_fl = NULL;
struct file_lock *new_fl2 = NULL;
struct file_lock *left = NULL;
struct file_lock *right = NULL;
- struct file_lock **before;
+ struct file_lock_context *ctx;
int error;
bool added = false;
LIST_HEAD(dispose);

+ ctx = locks_get_lock_context(inode);
+ if (!ctx)
+ return -ENOMEM;
+
/*
* We may need two file_lock structures for this operation,
* so we get them in advance to avoid races.
@@ -1000,15 +1008,14 @@ static int __posix_lock_file(struct inode *inode, struct file_lock *request, str
new_fl2 = locks_alloc_lock();
}

- spin_lock(&inode->i_lock);
+ spin_lock(&ctx->flc_lock);
/*
* New lock request. Walk all POSIX locks and look for conflicts. If
* there are any, either return error or put the request on the
* blocker's list of waiters and the global blocked_hash.
*/
if (request->fl_type != F_UNLCK) {
- for_each_lock(inode, before) {
- fl = *before;
+ list_for_each_entry(fl, &ctx->flc_posix, fl_list) {
if (!IS_POSIX(fl))
continue;
if (!posix_locks_conflict(request, fl))
@@ -1038,29 +1045,25 @@ static int __posix_lock_file(struct inode *inode, struct file_lock *request, str
if (request->fl_flags & FL_ACCESS)
goto out;

- /*
- * Find the first old lock with the same owner as the new lock.
- */
-
- before = &inode->i_flock;
-
- /* First skip locks owned by other processes. */
- while ((fl = *before) && (!IS_POSIX(fl) ||
- !posix_same_owner(request, fl))) {
- before = &fl->fl_next;
+ /* Find the first old lock with the same owner as the new lock */
+ list_for_each_entry(fl, &ctx->flc_posix, fl_list) {
+ if (posix_same_owner(request, fl))
+ break;
}

/* Process locks with this owner. */
- while ((fl = *before) && posix_same_owner(request, fl)) {
- /* Detect adjacent or overlapping regions (if same lock type)
- */
+ list_for_each_entry_safe_from(fl, tmp, &ctx->flc_posix, fl_list) {
+ if (!posix_same_owner(request, fl))
+ break;
+
+ /* Detect adjacent or overlapping regions (if same lock type) */
if (request->fl_type == fl->fl_type) {
/* In all comparisons of start vs end, use
* "start - 1" rather than "end + 1". If end
* is OFFSET_MAX, end + 1 will become negative.
*/
if (fl->fl_end < request->fl_start - 1)
- goto next_lock;
+ continue;
/* If the next lock in the list has entirely bigger
* addresses than the new one, insert the lock here.
*/
@@ -1081,18 +1084,17 @@ static int __posix_lock_file(struct inode *inode, struct file_lock *request, str
else
request->fl_end = fl->fl_end;
if (added) {
- locks_delete_lock(before, &dispose);
+ locks_delete_lock_ctx(fl, &dispose);
continue;
}
request = fl;
added = true;
- }
- else {
+ } else {
/* Processing for different lock types is a bit
* more complex.
*/
if (fl->fl_end < request->fl_start)
- goto next_lock;
+ continue;
if (fl->fl_start > request->fl_end)
break;
if (request->fl_type == F_UNLCK)
@@ -1111,7 +1113,7 @@ static int __posix_lock_file(struct inode *inode, struct file_lock *request, str
* one (This may happen several times).
*/
if (added) {
- locks_delete_lock(before, &dispose);
+ locks_delete_lock_ctx(fl, &dispose);
continue;
}
/*
@@ -1127,15 +1129,11 @@ static int __posix_lock_file(struct inode *inode, struct file_lock *request, str
locks_copy_lock(new_fl, request);
request = new_fl;
new_fl = NULL;
- locks_delete_lock(before, &dispose);
- locks_insert_lock(before, request);
+ locks_insert_lock_ctx(request, &fl->fl_list);
+ locks_delete_lock_ctx(fl, &dispose);
added = true;
}
}
- /* Go on to next lock.
- */
- next_lock:
- before = &fl->fl_next;
}

/*
@@ -1160,7 +1158,7 @@ static int __posix_lock_file(struct inode *inode, struct file_lock *request, str
goto out;
}
locks_copy_lock(new_fl, request);
- locks_insert_lock(before, new_fl);
+ locks_insert_lock_ctx(new_fl, &fl->fl_list);
new_fl = NULL;
}
if (right) {
@@ -1171,7 +1169,7 @@ static int __posix_lock_file(struct inode *inode, struct file_lock *request, str
left = new_fl2;
new_fl2 = NULL;
locks_copy_lock(left, right);
- locks_insert_lock(before, left);
+ locks_insert_lock_ctx(left, &fl->fl_list);
}
right->fl_start = request->fl_end + 1;
locks_wake_up_blocks(right);
@@ -1181,7 +1179,7 @@ static int __posix_lock_file(struct inode *inode, struct file_lock *request, str
locks_wake_up_blocks(left);
}
out:
- spin_unlock(&inode->i_lock);
+ spin_unlock(&ctx->flc_lock);
/*
* Free any unused locks.
*/
@@ -1251,22 +1249,29 @@ EXPORT_SYMBOL(posix_lock_file_wait);
*/
int locks_mandatory_locked(struct file *file)
{
+ int ret;
struct inode *inode = file_inode(file);
+ struct file_lock_context *ctx;
struct file_lock *fl;

+ ctx = inode->i_flctx;
+ if (!ctx)
+ return 0;
+
/*
* Search the lock list for this inode for any POSIX locks.
*/
- spin_lock(&inode->i_lock);
- for (fl = inode->i_flock; fl != NULL; fl = fl->fl_next) {
- if (!IS_POSIX(fl))
- continue;
+ spin_lock(&ctx->flc_lock);
+ ret = 0;
+ list_for_each_entry(fl, &ctx->flc_posix, fl_list) {
if (fl->fl_owner != current->files &&
- fl->fl_owner != file)
+ fl->fl_owner != file) {
+ ret = -EAGAIN;
break;
+ }
}
- spin_unlock(&inode->i_lock);
- return fl ? -EAGAIN : 0;
+ spin_unlock(&ctx->flc_lock);
+ return ret;
}

/**
@@ -2389,7 +2394,7 @@ void locks_remove_posix(struct file *filp, fl_owner_t owner)
* posix_lock_file(). Another process could be setting a lock on this
* file at the same time, but we wouldn't remove that lock anyway.
*/
- if (!file_inode(filp)->i_flock)
+ if (!file_inode(filp)->i_flctx)
return;

lock.fl_type = F_UNLCK;
diff --git a/fs/read_write.c b/fs/read_write.c
index 009d8542a889..0c77edf9fa25 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -358,7 +358,7 @@ int rw_verify_area(int read_write, struct file *file, const loff_t *ppos, size_t
return retval;
}

- if (unlikely(inode->i_flock && mandatory_lock(inode))) {
+ if (unlikely(inode->i_flctx && mandatory_lock(inode))) {
retval = locks_mandatory_area(
read_write == READ ? FLOCK_VERIFY_READ : FLOCK_VERIFY_WRITE,
inode, file, pos, count);
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 303dfcd3b663..9cdbda752b13 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -938,6 +938,7 @@ struct file_lock {
struct file_lock_context {
spinlock_t flc_lock;
struct list_head flc_flock;
+ struct list_head flc_posix;
};

/* The following constant reflects the upper bound of the file/locking space */
@@ -1920,7 +1921,7 @@ static inline int locks_verify_truncate(struct inode *inode,
struct file *filp,
loff_t size)
{
- if (inode->i_flock && mandatory_lock(inode))
+ if (inode->i_flctx && mandatory_lock(inode))
return locks_mandatory_area(
FLOCK_VERIFY_WRITE, inode, filp,
size < inode->i_size ? size : inode->i_size,
--
1.9.3