gfs2: Align read and write chunks to the page cache

Align the chunks that reads and writes are carried out in to the page
cache rather than the user buffers.  This will be more efficient in
general, especially for allocating writes.  Optimizing the case that the
user buffer is gfs2 backed isn't very useful; we only need to make sure
we won't deadlock.

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>

diff --git a/fs/gfs2/file.c b/fs/gfs2/file.c
index ea87bef7314d0e904b0c642395ea67258e612be7..11c46407d4a87ed7467a5cc724fc255aa0e7959b 100644 (file)
--- a/fs/gfs2/file.c
+++ b/fs/gfs2/file.c
@@ -771,6 +771,7 @@ static int gfs2_fsync(struct file *file, loff_t start, loff_t end,
 }
 
 static inline bool should_fault_in_pages(struct iov_iter *i,
+                                        struct kiocb *iocb,
                                         size_t *prev_count,
                                         size_t *window_size)
 {
@@ -783,15 +784,13 @@ static inline bool should_fault_in_pages(struct iov_iter *i,
                return false;
 
        size = PAGE_SIZE;
-       offs = offset_in_page(i->iov[0].iov_base + i->iov_offset);
+       offs = offset_in_page(iocb->ki_pos);
        if (*prev_count != count || !*window_size) {
                size_t nr_dirtied;
 
-               size = ALIGN(offs + count, PAGE_SIZE);
-               size = min_t(size_t, size, SZ_1M);
                nr_dirtied = max(current->nr_dirtied_pause -
                                 current->nr_dirtied, 8);
-               size = min(size, nr_dirtied << PAGE_SHIFT);
+               size = min_t(size_t, SZ_1M, nr_dirtied << PAGE_SHIFT);
        }
 
        *prev_count = count;
@@ -845,7 +844,7 @@ retry_under_glock:
        if (ret > 0)
                read = ret;
 
-       if (should_fault_in_pages(to, &prev_count, &window_size)) {
+       if (should_fault_in_pages(to, iocb, &prev_count, &window_size)) {
                gfs2_holder_allow_demote(gh);
                window_size -= fault_in_iov_iter_writeable(to, window_size);
                gfs2_holder_disallow_demote(gh);
@@ -916,7 +915,7 @@ retry_under_glock:
        if (ret > 0)
                written = ret;
 
-       if (should_fault_in_pages(from, &prev_count, &window_size)) {
+       if (should_fault_in_pages(from, iocb, &prev_count, &window_size)) {
                gfs2_holder_allow_demote(gh);
                window_size -= fault_in_iov_iter_readable(from, window_size);
                gfs2_holder_disallow_demote(gh);
@@ -984,7 +983,7 @@ retry_under_glock:
        if (ret > 0)
                read += ret;
 
-       if (should_fault_in_pages(to, &prev_count, &window_size)) {
+       if (should_fault_in_pages(to, iocb, &prev_count, &window_size)) {
                gfs2_holder_allow_demote(&gh);
                window_size -= fault_in_iov_iter_writeable(to, window_size);
                gfs2_holder_disallow_demote(&gh);
@@ -1061,7 +1060,7 @@ retry_under_glock:
                goto out_unlock;
 
        from->count = orig_count - written;
-       if (should_fault_in_pages(from, &prev_count, &window_size)) {
+       if (should_fault_in_pages(from, iocb, &prev_count, &window_size)) {
                gfs2_holder_allow_demote(gh);
                window_size -= fault_in_iov_iter_readable(from, window_size);
                gfs2_holder_disallow_demote(gh);