Commit 2b1ac852 authored by Yan, Zheng's avatar Yan, Zheng Committed by Ilya Dryomov
Browse files

ceph: try getting buffer capability for readahead/fadvise 



For readahead/fadvise cases, caller of ceph_readpages does not
hold buffer capability. Pages can be added to page cache while
there is no buffer capability. This can cause data integrity
issue.

Signed-off-by: default avatarYan, Zheng <zyan@redhat.com>
parent 5c341ee3

fs/ceph/addr.c

+48 −10
Original line number Diff line number Diff line
@@ -315,7 +315,32 @@ static int start_read(struct inode *inode, struct list_head *page_list, int max) 
	struct page **pages;

	pgoff_t next_index;

	int nr_pages = 0;

	int ret;

	int got = 0;

	int ret = 0;



	if (!current->journal_info) {

		/* caller of readpages does not hold buffer and read caps

		 * (fadvise, madvise and readahead cases) */

		int want = CEPH_CAP_FILE_CACHE;

		ret = ceph_try_get_caps(ci, CEPH_CAP_FILE_RD, want, &got);

		if (ret < 0) {

			dout("start_read %p, error getting cap\n", inode);

		} else if (!(got & want)) {

			dout("start_read %p, no cache cap\n", inode);

			ret = 0;

		}

		if (ret <= 0) {

			if (got)

				ceph_put_cap_refs(ci, got);

			while (!list_empty(page_list)) {

				page = list_entry(page_list->prev,

						  struct page, lru);

				list_del(&page->lru);

				put_page(page);

			}

			return ret;

		}

	}



	off = (u64) page_offset(page);
@@ -338,15 +363,18 @@ static int start_read(struct inode *inode, struct list_head *page_list, int max) 
				    CEPH_OSD_FLAG_READ, NULL,

				    ci->i_truncate_seq, ci->i_truncate_size,

				    false);

	if (IS_ERR(req))

		return PTR_ERR(req);

	if (IS_ERR(req)) {

		ret = PTR_ERR(req);

		goto out;

	}



	/* build page vector */

	nr_pages = calc_pages_for(0, len);

	pages = kmalloc(sizeof(*pages) * nr_pages, GFP_KERNEL);

	if (!pages) {

		ret = -ENOMEM;

	if (!pages)

		goto out;

		goto out_put;

	}

	for (i = 0; i < nr_pages; ++i) {

		page = list_entry(page_list->prev, struct page, lru);

		BUG_ON(PageLocked(page));
@@ -378,6 +406,12 @@ static int start_read(struct inode *inode, struct list_head *page_list, int max) 
	if (ret < 0)

		goto out_pages;

	ceph_osdc_put_request(req);



	/* After adding locked pages to page cache, the inode holds cache cap.

	 * So we can drop our cap refs. */

	if (got)

		ceph_put_cap_refs(ci, got);



	return nr_pages;



out_pages:
@@ -386,8 +420,11 @@ static int start_read(struct inode *inode, struct list_head *page_list, int max) 
		unlock_page(pages[i]);

	}

	ceph_put_page_vector(pages, nr_pages, false);

out:

out_put:

	ceph_osdc_put_request(req);

out:

	if (got)

		ceph_put_cap_refs(ci, got);

	return ret;

}
@@ -424,7 +461,6 @@ static int ceph_readpages(struct file *file, struct address_space *mapping, 
		rc = start_read(inode, page_list, max);

		if (rc < 0)

			goto out;

		BUG_ON(rc == 0);

	}

out:

	ceph_fscache_readpages_cancel(inode, page_list);
@@ -1371,9 +1407,11 @@ static int ceph_filemap_fault(struct vm_area_struct *vma, struct vm_fault *vmf) 
	     inode, off, (size_t)PAGE_SIZE, ceph_cap_string(got));



	if ((got & (CEPH_CAP_FILE_CACHE | CEPH_CAP_FILE_LAZYIO)) ||

	    ci->i_inline_version == CEPH_INLINE_NONE)

	    ci->i_inline_version == CEPH_INLINE_NONE) {

		current->journal_info = vma->vm_file;

		ret = filemap_fault(vma, vmf);

	else

		current->journal_info = NULL;

	} else

		ret = -EAGAIN;



	dout("filemap_fault %p %llu~%zd dropping cap refs on %s ret %d\n",

fs/ceph/caps.c

+21 −0
Original line number Diff line number Diff line
@@ -2479,6 +2479,27 @@ static void check_max_size(struct inode *inode, loff_t endoff) 
		ceph_check_caps(ci, CHECK_CAPS_AUTHONLY, NULL);

}



int ceph_try_get_caps(struct ceph_inode_info *ci, int need, int want, int *got)

{

	int ret, err = 0;



	BUG_ON(need & ~CEPH_CAP_FILE_RD);

	BUG_ON(want & ~(CEPH_CAP_FILE_CACHE|CEPH_CAP_FILE_LAZYIO));

	ret = ceph_pool_perm_check(ci, need);

	if (ret < 0)

		return ret;



	ret = try_get_cap_refs(ci, need, want, 0, true, got, &err);

	if (ret) {

		if (err == -EAGAIN) {

			ret = 0;

		} else if (err < 0) {

			ret = err;

		}

	}

	return ret;

}



/*

 * Wait for caps, and take cap references.  If we can't get a WR cap

 * due to a small max_size, make sure we check_max_size (and possibly

fs/ceph/file.c

+2 −1
Original line number Diff line number Diff line
@@ -1249,8 +1249,9 @@ static ssize_t ceph_read_iter(struct kiocb *iocb, struct iov_iter *to) 
		dout("aio_read %p %llx.%llx %llu~%u got cap refs on %s\n",

		     inode, ceph_vinop(inode), iocb->ki_pos, (unsigned)len,

		     ceph_cap_string(got));



		current->journal_info = filp;

		ret = generic_file_read_iter(iocb, to);

		current->journal_info = NULL;

	}

	dout("aio_read %p %llx.%llx dropping cap refs on %s = %d\n",

	     inode, ceph_vinop(inode), ceph_cap_string(got), (int)ret);

fs/ceph/super.h

+2 −0
Original line number Diff line number Diff line
@@ -905,6 +905,8 @@ extern int ceph_encode_dentry_release(void **p, struct dentry *dn, 


extern int ceph_get_caps(struct ceph_inode_info *ci, int need, int want,

			 loff_t endoff, int *got, struct page **pinned_page);

extern int ceph_try_get_caps(struct ceph_inode_info *ci,

			     int need, int want, int *got);



/* for counting open files by mode */

extern void __ceph_get_fmode(struct ceph_inode_info *ci, int mode);