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nfs: take i_mutex during direct I/O reads 

We'll need the i_mutex to prevent i_dio_count from incrementing while
truncate is waiting for it to reach zero, and protects against having
the pagecache repopulated after we flushed it.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
This commit is contained in:
Christoph Hellwig 2013-11-14 08:50:33 -08:00 committed by Trond Myklebust
parent 22cd1bf148
commit d0b9875d65
1 changed files with 12 additions and 2 deletions
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14
fs/nfs/direct.c
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@ -500,16 +500,17 @@ ssize_t nfs_file_direct_read(struct kiocb *iocb, const struct iovec *iov,
if (!count) if (!count)
goto out; goto out;
mutex_lock(&inode->i_mutex);
result = nfs_sync_mapping(mapping); result = nfs_sync_mapping(mapping);
if (result) if (result)
goto out; goto out_unlock;
task_io_account_read(count); task_io_account_read(count);
result = -ENOMEM; result = -ENOMEM;
dreq = nfs_direct_req_alloc(); dreq = nfs_direct_req_alloc();
if (dreq == NULL) if (dreq == NULL)
goto out; goto out_unlock;
dreq->inode = inode; dreq->inode = inode;
dreq->bytes_left = iov_length(iov, nr_segs); dreq->bytes_left = iov_length(iov, nr_segs);
@ -525,13 +526,22 @@ ssize_t nfs_file_direct_read(struct kiocb *iocb, const struct iovec *iov,
NFS_I(inode)->read_io += iov_length(iov, nr_segs); NFS_I(inode)->read_io += iov_length(iov, nr_segs);
result = nfs_direct_read_schedule_iovec(dreq, iov, nr_segs, pos, uio); result = nfs_direct_read_schedule_iovec(dreq, iov, nr_segs, pos, uio);
mutex_unlock(&inode->i_mutex);
if (!result) { if (!result) {
result = nfs_direct_wait(dreq); result = nfs_direct_wait(dreq);
if (result > 0) if (result > 0)
iocb->ki_pos = pos + result; iocb->ki_pos = pos + result;
} }
nfs_direct_req_release(dreq);
return result;
out_release: out_release:
nfs_direct_req_release(dreq); nfs_direct_req_release(dreq);
out_unlock:
mutex_unlock(&inode->i_mutex);
out: out:
return result; return result;
} }