Fix at least one source of the continued 'NFS append race'. close()
was calling nfs_flush() and then clearing the NMODIFIED bit. This is not legal since there might still be dirty buffers after the nfs_flush (for example, pending commits). The clearing of this bit in turn prevented a necessary vinvalbuf() from occuring leaving left over dirty buffers even after truncating the file in a new operation. The fix is to simply not clear NMODIFIED. Also added a sysctl vfs.nfs.nfsv3_commit_on_close which, if set to 1, will cause close() to do a stage 1 write AND a stage 2 commit synchronously. By default only the stage 1 write is done synchronously. Reviewed by: Alfred Perlstein <bright@wintelcom.net>
This commit is contained in:
parent
1780425711
commit
54986abd15
Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=55423
@ -251,6 +251,9 @@ static int nfsaccess_cache_timeout = NFS_MAXATTRTIMO;
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SYSCTL_INT(_vfs_nfs, OID_AUTO, access_cache_timeout, CTLFLAG_RW,
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&nfsaccess_cache_timeout, 0, "NFS ACCESS cache timeout");
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static int nfsv3_commit_on_close = 0;
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SYSCTL_INT(_vfs_nfs, OID_AUTO, nfsv3_commit_on_close, CTLFLAG_RW,
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&nfsv3_commit_on_close, 0, "write+commit on close, else only write");
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#if 0
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SYSCTL_INT(_vfs_nfs, OID_AUTO, access_cache_hits, CTLFLAG_RD,
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&nfsstats.accesscache_hits, 0, "NFS ACCESS cache hit count");
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@ -561,10 +564,25 @@ nfs_close(ap)
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if ((VFSTONFS(vp->v_mount)->nm_flag & NFSMNT_NQNFS) == 0 &&
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(np->n_flag & NMODIFIED)) {
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if (NFS_ISV3(vp)) {
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error = nfs_flush(vp, ap->a_cred, MNT_WAIT, ap->a_p, 0);
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np->n_flag &= ~NMODIFIED;
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} else
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/*
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* Under NFSv3 we have dirty buffers to dispose of. We
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* must flush them to the NFS server. We have the option
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* of waiting all the way through the commit rpc or just
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* waiting for the initial write. The default is to only
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* wait through the initial write so the data is in the
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* server's cache, which is roughly similar to the state
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* a standard disk subsystem leaves the file in on close().
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*
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* We cannot clear the NMODIFIED bit in np->n_flag due to
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* potential races with other processes, and certainly
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* cannot clear it if we don't commit.
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*/
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int cm = nfsv3_commit_on_close ? 1 : 0;
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error = nfs_flush(vp, ap->a_cred, MNT_WAIT, ap->a_p, cm);
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/* np->n_flag &= ~NMODIFIED; */
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} else {
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error = nfs_vinvalbuf(vp, V_SAVE, ap->a_cred, ap->a_p, 1);
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}
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np->n_attrstamp = 0;
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}
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if (np->n_flag & NWRITEERR) {
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@ -251,6 +251,9 @@ static int nfsaccess_cache_timeout = NFS_MAXATTRTIMO;
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SYSCTL_INT(_vfs_nfs, OID_AUTO, access_cache_timeout, CTLFLAG_RW,
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&nfsaccess_cache_timeout, 0, "NFS ACCESS cache timeout");
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static int nfsv3_commit_on_close = 0;
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SYSCTL_INT(_vfs_nfs, OID_AUTO, nfsv3_commit_on_close, CTLFLAG_RW,
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&nfsv3_commit_on_close, 0, "write+commit on close, else only write");
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#if 0
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SYSCTL_INT(_vfs_nfs, OID_AUTO, access_cache_hits, CTLFLAG_RD,
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&nfsstats.accesscache_hits, 0, "NFS ACCESS cache hit count");
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@ -561,10 +564,25 @@ nfs_close(ap)
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if ((VFSTONFS(vp->v_mount)->nm_flag & NFSMNT_NQNFS) == 0 &&
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(np->n_flag & NMODIFIED)) {
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if (NFS_ISV3(vp)) {
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error = nfs_flush(vp, ap->a_cred, MNT_WAIT, ap->a_p, 0);
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np->n_flag &= ~NMODIFIED;
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} else
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/*
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* Under NFSv3 we have dirty buffers to dispose of. We
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* must flush them to the NFS server. We have the option
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* of waiting all the way through the commit rpc or just
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* waiting for the initial write. The default is to only
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* wait through the initial write so the data is in the
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* server's cache, which is roughly similar to the state
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* a standard disk subsystem leaves the file in on close().
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*
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* We cannot clear the NMODIFIED bit in np->n_flag due to
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* potential races with other processes, and certainly
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* cannot clear it if we don't commit.
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*/
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int cm = nfsv3_commit_on_close ? 1 : 0;
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error = nfs_flush(vp, ap->a_cred, MNT_WAIT, ap->a_p, cm);
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/* np->n_flag &= ~NMODIFIED; */
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} else {
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error = nfs_vinvalbuf(vp, V_SAVE, ap->a_cred, ap->a_p, 1);
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}
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np->n_attrstamp = 0;
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}
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if (np->n_flag & NWRITEERR) {
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