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xfs: use i_mmaplock on read faults

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Take the i_mmaplock over read page faults. These come through the
->fault callout, so we need to wrap the generic implementation
with the i_mmaplock. While there, add tracepoints for the read
fault as it passes through XFS.

This gives us a lock order of mmap_sem -> i_mmaplock -> page_lock
-> i_lock.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
This commit is contained in:
Dave Chinner 2015-02-23 21:44:19 +11:00 committed by Dave Chinner
parent 653c60b633
commit de0e8c20ba
2 changed files with 29 additions and 1 deletions
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28
fs/xfs/xfs_file.c
View file

@ -1379,6 +1379,32 @@ xfs_file_llseek(
}
}
/*
* Locking for serialisation of IO during page faults. This results in a lock
* ordering of:
*
* mmap_sem (MM)
* i_mmap_lock (XFS - truncate serialisation)
* page_lock (MM)
* i_lock (XFS - extent map serialisation)
*/
STATIC int
xfs_filemap_fault(
struct vm_area_struct *vma,
struct vm_fault *vmf)
{
struct xfs_inode *ip = XFS_I(vma->vm_file->f_mapping->host);
int error;
trace_xfs_filemap_fault(ip);
xfs_ilock(ip, XFS_MMAPLOCK_SHARED);
error = filemap_fault(vma, vmf);
xfs_iunlock(ip, XFS_MMAPLOCK_SHARED);
return error;
}
const struct file_operations xfs_file_operations = {
.llseek = xfs_file_llseek,
.read = new_sync_read,
@ -1411,7 +1437,7 @@ const struct file_operations xfs_dir_file_operations = {
};
static const struct vm_operations_struct xfs_file_vm_ops = {
.fault = filemap_fault,
.fault = xfs_filemap_fault,
.map_pages = filemap_map_pages,
.page_mkwrite = xfs_vm_page_mkwrite,
};

2
fs/xfs/xfs_trace.h
View file

@ -685,6 +685,8 @@ DEFINE_INODE_EVENT(xfs_inode_set_eofblocks_tag);
DEFINE_INODE_EVENT(xfs_inode_clear_eofblocks_tag);
DEFINE_INODE_EVENT(xfs_inode_free_eofblocks_invalid);
DEFINE_INODE_EVENT(xfs_filemap_fault);
DECLARE_EVENT_CLASS(xfs_iref_class,
TP_PROTO(struct xfs_inode *ip, unsigned long caller_ip),
TP_ARGS(ip, caller_ip),