Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel...

[firefly-linux-kernel-4.4.55.git] / fs / kernfs / file.c

diff --git a/fs/kernfs/file.c b/fs/kernfs/file.c
index dbf397bfdff266d16332c57ac2de90e43ef8d8eb..8034706a7af87523bfc40e8660f21cc54238563f 100644 (file)
--- a/fs/kernfs/file.c
+++ b/fs/kernfs/file.c
@@ -252,10 +252,18 @@ static ssize_t kernfs_fop_write(struct file *file, const char __user *user_buf,
                                size_t count, loff_t *ppos)
 {
        struct kernfs_open_file *of = kernfs_of(file);
-       ssize_t len = min_t(size_t, count, PAGE_SIZE);
        const struct kernfs_ops *ops;
+       size_t len;
        char *buf;
 
+       if (of->atomic_write_len) {
+               len = count;
+               if (len > of->atomic_write_len)
+                       return -E2BIG;
+       } else {
+               len = min_t(size_t, count, PAGE_SIZE);
+       }
+
        buf = kmalloc(len + 1, GFP_KERNEL);
        if (!buf)
                return -ENOMEM;
@@ -652,6 +660,12 @@ static int kernfs_fop_open(struct inode *inode, struct file *file)
        of->kn = kn;
        of->file = file;
 
+       /*
+        * Write path needs to atomic_write_len outside active reference.
+        * Cache it in open_file.  See kernfs_fop_write() for details.
+        */
+       of->atomic_write_len = ops->atomic_write_len;
+
        /*
         * Always instantiate seq_file even if read access doesn't use
         * seq_file or is not requested.  This unifies private data access
@@ -820,7 +834,6 @@ struct kernfs_node *__kernfs_create_file(struct kernfs_node *parent,
                                         bool name_is_static,
                                         struct lock_class_key *key)
 {
-       struct kernfs_addrm_cxt acxt;
        struct kernfs_node *kn;
        unsigned flags;
        int rc;
@@ -855,10 +868,7 @@ struct kernfs_node *__kernfs_create_file(struct kernfs_node *parent,
        if (ops->mmap)
                kn->flags |= KERNFS_HAS_MMAP;
 
-       kernfs_addrm_start(&acxt);
-       rc = kernfs_add_one(&acxt, kn);
-       kernfs_addrm_finish(&acxt);
-
+       rc = kernfs_add_one(kn);
        if (rc) {
                kernfs_put(kn);
                return ERR_PTR(rc);