From 48bf2b1711dc498494e77705c415ee46bb508fd9 Mon Sep 17 00:00:00 2001 From: Steven Whitehouse Date: Wed, 29 Apr 2009 13:59:35 +0100 Subject: [PATCH] GFS2: Something nonlinear this way comes! For some reason GFS2 has been missing support for non-linear mappings. This patch fixes that, and also avoids taking any locks for mmap in the O_NOATIME case. In fact we don't actually need to take the lock here at all - just doing file_accessed() would be enough, but we have to take the lock eventually and this helps it hit disk (and thus be seen by other nodes) faster. Signed-off-by: Steven Whitehouse --- fs/gfs2/ops_file.c | 29 ++++++++++++++++------------- 1 file changed, 16 insertions(+), 13 deletions(-) diff --git a/fs/gfs2/ops_file.c b/fs/gfs2/ops_file.c index 5d82e91..0ee7bd2 100644 --- a/fs/gfs2/ops_file.c +++ b/fs/gfs2/ops_file.c @@ -425,33 +425,36 @@ static struct vm_operations_struct gfs2_vm_ops = { .page_mkwrite = gfs2_page_mkwrite, }; - /** * gfs2_mmap - * @file: The file to map * @vma: The VMA which described the mapping * - * Returns: 0 or error code + * There is no need to get a lock here unless we should be updating + * atime. We ignore any locking errors since the only consequence is + * a missed atime update (which will just be deferred until later). + * + * Returns: 0 */ static int gfs2_mmap(struct file *file, struct vm_area_struct *vma) { struct gfs2_inode *ip = GFS2_I(file->f_mapping->host); - struct gfs2_holder i_gh; - int error; - gfs2_holder_init(ip->i_gl, LM_ST_SHARED, 0, &i_gh); - error = gfs2_glock_nq(&i_gh); - if (error) { - gfs2_holder_uninit(&i_gh); - return error; - } + if (!(file->f_flags & O_NOATIME)) { + struct gfs2_holder i_gh; + int error; + gfs2_holder_init(ip->i_gl, LM_ST_EXCLUSIVE, 0, &i_gh); + error = gfs2_glock_nq(&i_gh); + file_accessed(file); + if (error == 0) + gfs2_glock_dq_uninit(&i_gh); + } vma->vm_ops = &gfs2_vm_ops; + vma->vm_flags |= VM_CAN_NONLINEAR; - gfs2_glock_dq_uninit(&i_gh); - - return error; + return 0; } /** -- 2.7.4