btrfs: fix NULL pointer dereference from free_reloc_roots()

[mirror_ubuntu-artful-kernel.git] / fs / read_write.c

diff --git a/fs/read_write.c b/fs/read_write.c
index 0cc7033aa413527973b92eb1a6bedda8e92da470..19fd0073d1dae91af9b1b6fa2d014a73dfd812b3 100644 (file)
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -112,7 +112,7 @@ generic_file_llseek_size(struct file *file, loff_t offset, int whence,
                 * In the generic case the entire file is data, so as long as
                 * offset isn't at the end of the file then the offset is data.
                 */
-               if (offset >= eof)
+               if ((unsigned long long)offset >= eof)
                        return -ENXIO;
                break;
        case SEEK_HOLE:
@@ -120,7 +120,7 @@ generic_file_llseek_size(struct file *file, loff_t offset, int whence,
                 * There is a virtual hole at the end of the file, so as long as
                 * offset isn't i_size or larger, return i_size.
                 */
-               if (offset >= eof)
+               if ((unsigned long long)offset >= eof)
                        return -ENXIO;
                offset = eof;
                break;
@@ -473,6 +473,30 @@ ssize_t __vfs_write(struct file *file, const char __user *p, size_t count,
 }
 EXPORT_SYMBOL(__vfs_write);
 
+vfs_readf_t vfs_readf(struct file *file)
+{
+       const struct file_operations *fop = file->f_op;
+
+       if (fop->read)
+               return fop->read;
+       if (fop->read_iter)
+               return new_sync_read;
+       return ERR_PTR(-ENOSYS);
+}
+EXPORT_SYMBOL_GPL(vfs_readf);
+
+vfs_writef_t vfs_writef(struct file *file)
+{
+       const struct file_operations *fop = file->f_op;
+
+       if (fop->write)
+               return fop->write;
+       if (fop->write_iter)
+               return new_sync_write;
+       return ERR_PTR(-ENOSYS);
+}
+EXPORT_SYMBOL_GPL(vfs_writef);
+
 ssize_t __kernel_write(struct file *file, const char *buf, size_t count, loff_t *pos)
 {
        mm_segment_t old_fs;