Re: [RFC PATCH v2 1/5] nfs: Fix write to swapfile failure due to generic_write_checks()
From: Matthew Wilcox <willy@infradead.org>
Date: 2021-08-13 03:10:43
Also in:
linux-fsdevel, linux-nfs, lkml
Subsystem:
filesystems (vfs and infrastructure), nfs, sunrpc, and lockd clients, the rest · Maintainers:
Alexander Viro, Christian Brauner, Trond Myklebust, Anna Schumaker, Linus Torvalds
On Thu, Aug 12, 2021 at 09:22:06PM +0100, David Howells wrote:
Trying to use a swapfile on NFS results in every DIO write failing with ETXTBSY because generic_write_checks(), as called by nfs_direct_write() from nfs_direct_IO(), forbids writes to swapfiles.
Why does nfs_direct_write() call generic_write_checks()? ie call generic_write_checks() earlier, and only swap would bypass them.
diff --git a/fs/nfs/direct.c b/fs/nfs/direct.c
index 2e894fec036b..7e2ca6b5fc5f 100644
--- a/fs/nfs/direct.c
+++ b/fs/nfs/direct.c@@ -905,9 +905,6 @@ ssize_t nfs_file_direct_write(struct kiocb *iocb, struct iov_iter *iter) dfprintk(FILE, "NFS: direct write(%pD2, %zd@%Ld)\n", file, iov_iter_count(iter), (long long) iocb->ki_pos); - result = generic_write_checks(iocb, iter); - if (result <= 0) - return result; count = result; nfs_add_stats(mapping->host, NFSIOS_DIRECTWRITTENBYTES, count);
diff --git a/fs/nfs/file.c b/fs/nfs/file.c
index 1fef107961bc..91b2e3214836 100644
--- a/fs/nfs/file.c
+++ b/fs/nfs/file.c@@ -611,6 +611,10 @@ ssize_t nfs_file_write(struct kiocb *iocb, struct iov_iter *from) errseq_t since; int error; + result = generic_write_checks(iocb, from); + if (result < 0) + return result; + result = nfs_key_timeout_notify(file, inode); if (result) return result;
@@ -621,8 +625,6 @@ ssize_t nfs_file_write(struct kiocb *iocb, struct iov_iter *from) dprintk("NFS: write(%pD2, %zu@%Ld)\n", file, iov_iter_count(from), (long long) iocb->ki_pos); - if (IS_SWAPFILE(inode)) - goto out_swapfile; /* * O_APPEND implies that we must revalidate the file length. */
@@ -636,7 +638,6 @@ ssize_t nfs_file_write(struct kiocb *iocb, struct iov_iter *from) since = filemap_sample_wb_err(file->f_mapping); nfs_start_io_write(inode); - result = generic_write_checks(iocb, from); if (result > 0) { current->backing_dev_info = inode_to_bdi(inode); result = generic_perform_write(file, from, iocb->ki_pos);
@@ -677,10 +678,6 @@ ssize_t nfs_file_write(struct kiocb *iocb, struct iov_iter *from) nfs_add_stats(inode, NFSIOS_NORMALWRITTENBYTES, written); out: return result; - -out_swapfile: - printk(KERN_INFO "NFS: attempt to write to active swap file!\n"); - return -ETXTBSY; } EXPORT_SYMBOL_GPL(nfs_file_write);