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Commit c3cd6283 authored by Sage Weil's avatar Sage Weil
Browse files

ceph: fix short sync reads from the OSD 



If we get a short read from the OSD because the object is small, we need to
zero the remainder of the buffer.  For O_DIRECT reads, the attempted range
is not trimmed to i_size by the VFS, so we were actually looping
indefinitely.

Fix by trimming by i_size, and the unconditionally zeroing the trailing
range.

Reported-by: default avatarJeff Wu <cpwu@tnsoft.com.cn>
Signed-off-by: default avatarSage Weil <sage@newdream.net>
parent 25845472

fs/ceph/file.c

+15 −13
Original line number Diff line number Diff line
@@ -283,7 +283,7 @@ int ceph_release(struct inode *inode, struct file *file) 
static int striped_read(struct inode *inode,

			u64 off, u64 len,

			struct page **pages, int num_pages,

			int *checkeof, bool align_to_pages,

			int *checkeof, bool o_direct,

			unsigned long buf_align)

{

	struct ceph_fs_client *fsc = ceph_inode_to_client(inode);
@@ -308,7 +308,7 @@ static int striped_read(struct inode *inode, 
	io_align = off & ~PAGE_MASK;



more:

	if (align_to_pages)

	if (o_direct)

		page_align = (pos - io_align + buf_align) & ~PAGE_MASK;

	else

		page_align = pos & ~PAGE_MASK;
@@ -346,20 +346,22 @@ static int striped_read(struct inode *inode, 
	}



	if (was_short) {

		/* was original extent fully inside i_size? */

		if (pos + left <= inode->i_size) {

			dout("zero tail\n");

			ceph_zero_page_vector_range(page_off + read, len - read,

		/* did we bounce off eof? */

		if (pos + left > inode->i_size)

			*checkeof = 1;



		/* zero trailing bytes (inside i_size) */

		if (left > 0 && pos < inode->i_size) {

			if (pos + left > inode->i_size)

				left = inode->i_size - pos;



			dout("zero tail %d\n", left);

			ceph_zero_page_vector_range(page_off + read, left,

						    pages);

			read = len;

			goto out;

			read += left;

		}



		/* check i_size */

		*checkeof = 1;

	}



out:

	if (ret >= 0)

		ret = read;

	dout("striped_read returns %d\n", ret);
@@ -659,7 +661,7 @@ static ssize_t ceph_aio_read(struct kiocb *iocb, const struct iovec *iov, 


		/* hit EOF or hole? */

		if (statret == 0 && *ppos < inode->i_size) {

			dout("aio_read sync_read hit hole, reading more\n");

			dout("aio_read sync_read hit hole, ppos %lld < size %lld, reading more\n", *ppos, inode->i_size);

			read += ret;

			base += ret;

			len -= ret;