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| author | Dan Aloni <dan.aloni@vastdata.com> | 2024-07-24 14:07:12 +0300 |
|---|---|---|
| committer | Anna Schumaker <anna.schumaker@oracle.com> | 2024-09-23 15:03:13 -0400 |
| commit | dfb07e990a0d019d7ae9b78dd4260620ce32e79a (patch) | |
| tree | 8463cc6c4b39ca3a466e55fd8cc051cec41d9304 /fs | |
| parent | 6d26c5e4d83cd39006bfd2ecbc97fbfac34aaefa (diff) | |
| download | lwn-dfb07e990a0d019d7ae9b78dd4260620ce32e79a.tar.gz lwn-dfb07e990a0d019d7ae9b78dd4260620ce32e79a.zip | |
nfs: add 'noalignwrite' option for lock-less 'lost writes' prevention
There are some applications that write to predefined non-overlapping
file offsets from multiple clients and therefore don't need to rely on
file locking. However, if these applications want non-aligned offsets
and sizes they need to either use locks or risk data corruption, as the
NFS client defaults to extending writes to whole pages.
This commit adds a new mount option `noalignwrite`, which allows to turn
that off and avoid the need of locking, as long as these applications
don't overlap on offsets.
Signed-off-by: Dan Aloni <dan.aloni@vastdata.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Anna Schumaker <anna.schumaker@oracle.com>
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/nfs/fs_context.c | 8 | ||||
| -rw-r--r-- | fs/nfs/super.c | 3 | ||||
| -rw-r--r-- | fs/nfs/write.c | 3 |
3 files changed, 14 insertions, 0 deletions
diff --git a/fs/nfs/fs_context.c b/fs/nfs/fs_context.c index 6c9f3f6645dd..7e000d782e28 100644 --- a/fs/nfs/fs_context.c +++ b/fs/nfs/fs_context.c @@ -49,6 +49,7 @@ enum nfs_param { Opt_bsize, Opt_clientaddr, Opt_cto, + Opt_alignwrite, Opt_fg, Opt_fscache, Opt_fscache_flag, @@ -149,6 +150,7 @@ static const struct fs_parameter_spec nfs_fs_parameters[] = { fsparam_u32 ("bsize", Opt_bsize), fsparam_string("clientaddr", Opt_clientaddr), fsparam_flag_no("cto", Opt_cto), + fsparam_flag_no("alignwrite", Opt_alignwrite), fsparam_flag ("fg", Opt_fg), fsparam_flag_no("fsc", Opt_fscache_flag), fsparam_string("fsc", Opt_fscache), @@ -592,6 +594,12 @@ static int nfs_fs_context_parse_param(struct fs_context *fc, else ctx->flags |= NFS_MOUNT_TRUNK_DISCOVERY; break; + case Opt_alignwrite: + if (result.negated) + ctx->flags |= NFS_MOUNT_NO_ALIGNWRITE; + else + ctx->flags &= ~NFS_MOUNT_NO_ALIGNWRITE; + break; case Opt_ac: if (result.negated) ctx->flags |= NFS_MOUNT_NOAC; diff --git a/fs/nfs/super.c b/fs/nfs/super.c index 97b386032b71..9723b6c53397 100644 --- a/fs/nfs/super.c +++ b/fs/nfs/super.c @@ -551,6 +551,9 @@ static void nfs_show_mount_options(struct seq_file *m, struct nfs_server *nfss, else seq_puts(m, ",local_lock=posix"); + if (nfss->flags & NFS_MOUNT_NO_ALIGNWRITE) + seq_puts(m, ",noalignwrite"); + if (nfss->flags & NFS_MOUNT_WRITE_EAGER) { if (nfss->flags & NFS_MOUNT_WRITE_WAIT) seq_puts(m, ",write=wait"); diff --git a/fs/nfs/write.c b/fs/nfs/write.c index 80c6ded5f74c..61b580bcb356 100644 --- a/fs/nfs/write.c +++ b/fs/nfs/write.c @@ -1295,7 +1295,10 @@ static int nfs_can_extend_write(struct file *file, struct folio *folio, struct file_lock_context *flctx = locks_inode_context(inode); struct file_lock *fl; int ret; + unsigned int mntflags = NFS_SERVER(inode)->flags; + if (mntflags & NFS_MOUNT_NO_ALIGNWRITE) + return 0; if (file->f_flags & O_DSYNC) return 0; if (!nfs_folio_write_uptodate(folio, pagelen)) |