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author | Fred Isaman <iisaman@citi.umich.edu> | 2008-03-19 11:24:39 -0400 |
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committer | Trond Myklebust <Trond.Myklebust@netapp.com> | 2008-03-19 17:59:02 -0400 |
commit | f8512ad0da16cbe156f3a7627971cdf0b39c4138 (patch) | |
tree | 2658c63faeda07505793ccc747ee4efbffdaa69c /fs/nfs/write.c | |
parent | 264e3e889d86e552b4191d69bb60f4f3b383135a (diff) | |
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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/nfs/write.c')
-rw-r--r-- | fs/nfs/write.c | 8 |
1 files changed, 7 insertions, 1 deletions
diff --git a/fs/nfs/write.c b/fs/nfs/write.c index 80c61fd..bed6341 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; } |