[PATCH 3/4] cachefiles: perform test on s_blocksize when opening cache file.

From	David Howells <dhowells@redhat.com>
Newsgroups	linux.kernel
Subject	[PATCH 3/4] cachefiles: perform test on s_blocksize when opening cache file.
Date	2015-11-04 16:30 +0100
Message-ID	<qr8aB-2cC-5@gated-at.bofh.it> (permalink)
References	<qr8aB-2cC-7@gated-at.bofh.it>
Organization	Red Hat UK Ltd. Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SI4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 3798903

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From: NeilBrown <neilb@suse.de>

cachefiles requires that s_blocksize in the cache is not greater than
PAGE_SIZE, and performs the check every time a block is accessed.

Move the test to the place where the file is "opened", where other
file-validity tests are performed.

Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: David Howells <dhowells@redhat.com>
---

 fs/cachefiles/namei.c |    2 ++
 fs/cachefiles/rdwr.c  |    6 ------
 2 files changed, 2 insertions(+), 6 deletions(-)

diff --git a/fs/cachefiles/namei.c b/fs/cachefiles/namei.c
index fc1056f5c96a..c4b893453e0e 100644
--- a/fs/cachefiles/namei.c
+++ b/fs/cachefiles/namei.c
@@ -655,6 +655,8 @@ lookup_again:
 			aops = d_backing_inode(object->dentry)->i_mapping->a_ops;
 			if (!aops->bmap)
 				goto check_error;
+			if (object->dentry->d_sb->s_blocksize > PAGE_SIZE)
+				goto check_error;
 
 			object->backer = object->dentry;
 		} else {
diff --git a/fs/cachefiles/rdwr.c b/fs/cachefiles/rdwr.c
index 3cbb0e834694..e76c2452ac40 100644
--- a/fs/cachefiles/rdwr.c
+++ b/fs/cachefiles/rdwr.c
@@ -414,9 +414,6 @@ int cachefiles_read_or_alloc_page(struct fscache_retrieval *op,
 	ASSERT(inode->i_mapping->a_ops->readpages);
 
 	/* calculate the shift required to use bmap */
-	if (inode->i_sb->s_blocksize > PAGE_SIZE)
-		goto enobufs;
-
 	shift = PAGE_SHIFT - inode->i_sb->s_blocksize_bits;
 
 	op->op.flags &= FSCACHE_OP_KEEP_FLAGS;
@@ -711,9 +708,6 @@ int cachefiles_read_or_alloc_pages(struct fscache_retrieval *op,
 	ASSERT(inode->i_mapping->a_ops->readpages);
 
 	/* calculate the shift required to use bmap */
-	if (inode->i_sb->s_blocksize > PAGE_SIZE)
-		goto all_enobufs;
-
 	shift = PAGE_SHIFT - inode->i_sb->s_blocksize_bits;
 
 	pagevec_init(&pagevec, 0);

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[PATCH 3/4] cachefiles: perform test on s_blocksize when opening  cache file. David Howells <dhowells@redhat.com> - 2015-11-04 16:30 +0100

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