From 48e03bc515cff75718de5460458680a230ae997e Mon Sep 17 00:00:00 2001 From: Trond Myklebust Date: Fri, 5 Jun 2009 12:35:15 -0400 Subject: [PATCH] nfsd: Use write gathering only with NFSv2 NFSv3 and above can use unstable writes whenever they are sending more than one write, rather than relying on the flaky write gathering heuristics. More often than not, write gathering is currently getting it wrong when the NFSv3 clients are sending a single write with FILE_SYNC for efficiency reasons. This patch turns off write gathering for NFSv3/v4, and ensures that it only applies to the one case that can actually benefit: namely NFSv2. Signed-off-by: Trond Myklebust Signed-off-by: J. Bruce Fields --- fs/nfsd/vfs.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c index b660435978d2..f30cc4eadb0a 100644 --- a/fs/nfsd/vfs.c +++ b/fs/nfsd/vfs.c @@ -975,6 +975,7 @@ nfsd_vfs_write(struct svc_rqst *rqstp, struct svc_fh *fhp, struct file *file, __be32 err = 0; int host_err; int stable = *stablep; + int use_wgather; #ifdef MSNFS err = nfserr_perm; @@ -993,9 +994,10 @@ nfsd_vfs_write(struct svc_rqst *rqstp, struct svc_fh *fhp, struct file *file, * - the sync export option has been set, or * - the client requested O_SYNC behavior (NFSv3 feature). * - The file system doesn't support fsync(). - * When gathered writes have been configured for this volume, + * When NFSv2 gathered writes have been configured for this volume, * flushing the data to disk is handled separately below. */ + use_wgather = (rqstp->rq_vers == 2) && EX_WGATHER(exp); if (!file->f_op->fsync) {/* COMMIT3 cannot work */ stable = 2; @@ -1004,7 +1006,7 @@ nfsd_vfs_write(struct svc_rqst *rqstp, struct svc_fh *fhp, struct file *file, if (!EX_ISSYNC(exp)) stable = 0; - if (stable && !EX_WGATHER(exp)) { + if (stable && !use_wgather) { spin_lock(&file->f_lock); file->f_flags |= O_SYNC; spin_unlock(&file->f_lock); @@ -1040,7 +1042,7 @@ nfsd_vfs_write(struct svc_rqst *rqstp, struct svc_fh *fhp, struct file *file, * nice and simple solution (IMHO), and it seems to * work:-) */ - if (EX_WGATHER(exp)) { + if (use_wgather) { if (atomic_read(&inode->i_writecount) > 1 || (last_ino == inode->i_ino && last_dev == inode->i_sb->s_dev)) { dprintk("nfsd: write defer %d\n", task_pid_nr(current)); -- GitLab