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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 <swhiteho@redhat.com>
This commit is contained in:
Steven Whitehouse 2009-04-29 13:59:35 +01:00
parent 4a0f9a321a
commit 48bf2b1711
1 changed files with 16 additions and 13 deletions
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29
fs/gfs2/ops_file.c
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@ -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;
}
/**