Placeholder pages allow DIO to use locking rules similar to that of
writepage. DIO can now fill holes, and it can extend the file via
get_block().
i_mutex can be dropped during writes if we are writing inside i_size.
Signed-off-by: Chris Mason <chris.mason@xxxxxxxxxx>
diff -r 317779b11fe1 -r ac51e7a4c7a6 fs/direct-io.c
--- a/fs/direct-io.c Thu Dec 21 15:31:30 2006 -0500
+++ b/fs/direct-io.c Thu Dec 21 15:31:30 2006 -0500
@@ -70,6 +70,7 @@ struct dio {
int rw;
loff_t i_size; /* i_size when submitted */
int lock_type; /* doesn't change */
+ int reacquire_i_mutex; /* should we get i_mutex when done? */
unsigned blkbits; /* doesn't change */
unsigned blkfactor; /* When we're using an alignment which
is finer than the filesystem's soft
@@ -218,8 +219,7 @@ static int lock_page_range(struct dio *d
return 0;
return find_or_insert_placeholders(mapping, dio->tmppages, start, end,
ARRAY_SIZE(dio->tmppages),
- GFP_KERNEL,
- dio->rw == READ);
+ GFP_KERNEL, 1);
}
@@ -282,6 +282,8 @@ static int dio_complete(struct dio *dio,
unlock_page_range(dio, dio->fspages_start_off,
dio->fspages_end_off - dio->fspages_start_off);
dio->fspages_end_off = dio->fspages_start_off;
+ if (dio->reacquire_i_mutex)
+ mutex_lock(&dio->inode->i_mutex);
if (ret == 0)
ret = dio->page_errors;
@@ -568,13 +570,8 @@ static int get_more_blocks(struct dio *d
map_bh->b_size = fs_count << dio->inode->i_blkbits;
create = dio->rw & WRITE;
- if (dio->lock_type == DIO_LOCKING) {
- if (dio->block_in_file < (i_size_read(dio->inode) >>
- dio->blkbits))
- create = 0;
- } else if (dio->lock_type == DIO_NO_LOCKING) {
+ if (dio->lock_type == DIO_NO_LOCKING)
create = 0;
- }
index = fs_startblk >> (PAGE_CACHE_SHIFT -
dio->inode->i_blkbits);
end = (dio->final_block_in_request >> dio->blkfactor) >>
@@ -1258,6 +1255,13 @@ __blockdev_direct_IO(int rw, struct kioc
dio->is_async = !is_sync_kiocb(iocb) && !((rw & WRITE) &&
(end > i_size_read(inode)));
+ /* if our write is inside i_size, we can drop i_mutex */
+ dio->reacquire_i_mutex = 0;
+ if ((rw & WRITE) && dio_lock_type == DIO_LOCKING &&
+ end <= i_size_read(inode) && is_sync_kiocb(iocb)) {
+ dio->reacquire_i_mutex = 1;
+ mutex_unlock(&inode->i_mutex);
+ }
retval = direct_io_worker(rw, iocb, inode, iov, offset,
nr_segs, blkbits, get_block, end_io, dio);
out:
diff -r 317779b11fe1 -r ac51e7a4c7a6 mm/filemap.c
--- a/mm/filemap.c Thu Dec 21 15:31:30 2006 -0500
+++ b/mm/filemap.c Thu Dec 21 15:31:30 2006 -0500
@@ -2865,10 +2865,19 @@ generic_file_direct_IO(int rw, struct ki
retval = mapping->a_ops->direct_IO(rw, iocb, iov,
offset, nr_segs);
if (rw == WRITE && mapping->nrpages) {
+ int err;
pgoff_t end = (offset + write_len - 1)
>> PAGE_CACHE_SHIFT;
- int err = invalidate_inode_pages2_range(mapping,
- offset >> PAGE_CACHE_SHIFT, end);
+
+ /* O_DIRECT is allowed to drop i_mutex, so more data
+ * could have been dirtied by others. Start io one more
+ * time
+ */
+ err = filemap_fdatawrite_range(mapping, offset,
+ offset + write_len - 1);
+ if (!err)
+ err = invalidate_inode_pages2_range(mapping,
+ offset >> PAGE_CACHE_SHIFT, end);
if (err)
retval = err;
}
-
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