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authorFred Isaman <iisaman@citi.umich.edu>2008-03-19 11:24:39 -0400
committerTrond Myklebust <Trond.Myklebust@netapp.com>2008-03-19 17:59:02 -0400
commitf8512ad0da16cbe156f3a7627971cdf0b39c4138 (patch)
tree2658c63faeda07505793ccc747ee4efbffdaa69c /fs
parent264e3e889d86e552b4191d69bb60f4f3b383135a (diff)
downloadvexpress-lsk-f8512ad0da16cbe156f3a7627971cdf0b39c4138.tar.gz
nfs: don't ignore return value from nfs_pageio_add_request
Ignoring the return value from nfs_pageio_add_request can cause deadlocks. In read path: call nfs_pageio_add_request from readpage_async_filler assume at this point that there are requests already in desc, that can't be merged with the current request. so nfs_pageio_doio is fired up to clear out desc. assume something goes wrong in setting up the io, so desc->pg_error is set. This causes nfs_pageio_add_request to return 0, *WITHOUT* adding the original request. BUT, since return code is ignored, readpage_async_filler assumes it has been added, and does nothing further, leaving page locked. do_generic_mapping_read will eventually call lock_page, resulting in deadlock In write path: page is marked dirty by generic_perform_write nfs_writepages is called call nfs_pageio_add_request from nfs_page_async_flush assume at this point that there are requests already in desc, that can't be merged with the current request. so nfs_pageio_doio is fired up to clear out desc. assume something goes wrong in setting up the io, so desc->pg_error is set. This causes nfs_page_async_flush to return 0, *WITHOUT* adding the original request, yet marking the request as locked (PG_BUSY) and in writeback, clearing dirty marks. The next time a write is done to the page, deadlock will result as nfs_write_end calls nfs_update_request Signed-off-by: Fred Isaman <iisaman@citi.umich.edu> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Diffstat (limited to 'fs')
-rw-r--r--fs/nfs/read.c5
-rw-r--r--fs/nfs/write.c8
2 files changed, 11 insertions, 2 deletions
diff --git a/fs/nfs/read.c b/fs/nfs/read.c
index 3d7d9631e12..5a70be589bb 100644
--- a/fs/nfs/read.c
+++ b/fs/nfs/read.c
@@ -533,7 +533,10 @@ readpage_async_filler(void *data, struct page *page)
if (len < PAGE_CACHE_SIZE)
zero_user_segment(page, len, PAGE_CACHE_SIZE);
- nfs_pageio_add_request(desc->pgio, new);
+ if (!nfs_pageio_add_request(desc->pgio, new)) {
+ error = desc->pgio->pg_error;
+ goto out_unlock;
+ }
return 0;
out_error:
error = PTR_ERR(new);
diff --git a/fs/nfs/write.c b/fs/nfs/write.c
index 80c61fdb272..bed63416a55 100644
--- a/fs/nfs/write.c
+++ b/fs/nfs/write.c
@@ -39,6 +39,7 @@ static struct nfs_page * nfs_update_request(struct nfs_open_context*,
unsigned int, unsigned int);
static void nfs_pageio_init_write(struct nfs_pageio_descriptor *desc,
struct inode *inode, int ioflags);
+static void nfs_redirty_request(struct nfs_page *req);
static const struct rpc_call_ops nfs_write_partial_ops;
static const struct rpc_call_ops nfs_write_full_ops;
static const struct rpc_call_ops nfs_commit_ops;
@@ -288,7 +289,12 @@ static int nfs_page_async_flush(struct nfs_pageio_descriptor *pgio,
BUG();
}
spin_unlock(&inode->i_lock);
- nfs_pageio_add_request(pgio, req);
+ if (!nfs_pageio_add_request(pgio, req)) {
+ nfs_redirty_request(req);
+ nfs_end_page_writeback(page);
+ nfs_clear_page_tag_locked(req);
+ return pgio->pg_error;
+ }
return 0;
}