FreeBSD/Linux Kernel Cross Reference
sys/fs/stack.c

     #include <linux/export.h>
     #include <linux/fs.h>
     #include <linux/fs_stack.h>
     
     /* does _NOT_ require i_mutex to be held.
      *
      * This function cannot be inlined since i_size_{read,write} is rather
      * heavy-weight on 32-bit systems
      */
    void fsstack_copy_inode_size(struct inode *dst, struct inode *src)
    {
            loff_t i_size;
            blkcnt_t i_blocks;
    
            /*
             * i_size_read() includes its own seqlocking and protection from
             * preemption (see include/linux/fs.h): we need nothing extra for
             * that here, and prefer to avoid nesting locks than attempt to keep
             * i_size and i_blocks in sync together.
             */
            i_size = i_size_read(src);
    
            /*
             * But if CONFIG_LBDAF (on 32-bit), we ought to make an effort to
             * keep the two halves of i_blocks in sync despite SMP or PREEMPT -
             * though stat's generic_fillattr() doesn't bother, and we won't be
             * applying quotas (where i_blocks does become important) at the
             * upper level.
             *
             * We don't actually know what locking is used at the lower level;
             * but if it's a filesystem that supports quotas, it will be using
             * i_lock as in inode_add_bytes().
             */
            if (sizeof(i_blocks) > sizeof(long))
                    spin_lock(&src->i_lock);
            i_blocks = src->i_blocks;
            if (sizeof(i_blocks) > sizeof(long))
                    spin_unlock(&src->i_lock);
    
            /*
             * If CONFIG_SMP or CONFIG_PREEMPT on 32-bit, it's vital for
             * fsstack_copy_inode_size() to hold some lock around
             * i_size_write(), otherwise i_size_read() may spin forever (see
             * include/linux/fs.h).  We don't necessarily hold i_mutex when this
             * is called, so take i_lock for that case.
             *
             * And if CONFIG_LBADF (on 32-bit), continue our effort to keep the
             * two halves of i_blocks in sync despite SMP or PREEMPT: use i_lock
             * for that case too, and do both at once by combining the tests.
             *
             * There is none of this locking overhead in the 64-bit case.
             */
            if (sizeof(i_size) > sizeof(long) || sizeof(i_blocks) > sizeof(long))
                    spin_lock(&dst->i_lock);
            i_size_write(dst, i_size);
            dst->i_blocks = i_blocks;
            if (sizeof(i_size) > sizeof(long) || sizeof(i_blocks) > sizeof(long))
                    spin_unlock(&dst->i_lock);
    }
    EXPORT_SYMBOL_GPL(fsstack_copy_inode_size);
    
    /* copy all attributes */
    void fsstack_copy_attr_all(struct inode *dest, const struct inode *src)
    {
            dest->i_mode = src->i_mode;
            dest->i_uid = src->i_uid;
            dest->i_gid = src->i_gid;
            dest->i_rdev = src->i_rdev;
            dest->i_atime = src->i_atime;
            dest->i_mtime = src->i_mtime;
            dest->i_ctime = src->i_ctime;
            dest->i_blkbits = src->i_blkbits;
            dest->i_flags = src->i_flags;
            set_nlink(dest, src->i_nlink);
    }
    EXPORT_SYMBOL_GPL(fsstack_copy_attr_all);

Cache object: 238020064c4a3090ed47a84677fd042d