| Message ID | 1404143423-24381-3-git-send-email-jlayton@primarydata.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Mon, Jun 30, 2014 at 11:48:31AM -0400, Jeff Layton wrote: > From: Trond Myklebust <trond.myklebust@primarydata.com> > > Ensure that we only can have a single struct nfs4_file per inode > in the file_hashtbl and make addition atomic with respect to lookup. This changelog gives the impression it's a bugfix, and it isn't. I understand it's tedious in this series, but really I think at a minimum a changelog should always make it clear whether a patch is a bugfix or not. Applying with changelog rewritten to: Current code depends on the client_mutex to guarantee a single struct nfs4_file per inode in the file_hashtbl and make addition atomic with respect to lookup. Rely instead on the state_Lock, to make it easier to stop taking the client_mutex here later. ... --b. > > To prevent an i_lock/state_lock inversion, change nfsd4_init_file to > use ihold instead if igrab. That's also more efficient anyway as we > definitely hold a reference to the inode at that point. > > Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com> > Signed-off-by: Jeff Layton <jlayton@primarydata.com> > Reviewed-by: Christoph Hellwig <hch@lst.de> > --- > fs/nfsd/nfs4state.c | 49 +++++++++++++++++++++++++++++++++++++------------ > 1 file changed, 37 insertions(+), 12 deletions(-) > > diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c > index c473bd6d52c8..29788fd0da24 100644 > --- a/fs/nfsd/nfs4state.c > +++ b/fs/nfsd/nfs4state.c > @@ -2611,17 +2611,18 @@ static void nfsd4_init_file(struct nfs4_file *fp, struct inode *ino) > { > unsigned int hashval = file_hashval(ino); > > + lockdep_assert_held(&state_lock); > + > atomic_set(&fp->fi_ref, 1); > INIT_LIST_HEAD(&fp->fi_stateids); > INIT_LIST_HEAD(&fp->fi_delegations); > - fp->fi_inode = igrab(ino); > + ihold(ino); > + fp->fi_inode = ino; > fp->fi_had_conflict = false; > fp->fi_lease = NULL; > memset(fp->fi_fds, 0, sizeof(fp->fi_fds)); > memset(fp->fi_access, 0, sizeof(fp->fi_access)); > - spin_lock(&state_lock); > hlist_add_head(&fp->fi_hash, &file_hashtbl[hashval]); > - spin_unlock(&state_lock); > } > > void > @@ -2787,23 +2788,49 @@ find_openstateowner_str(unsigned int hashval, struct nfsd4_open *open, > > /* search file_hashtbl[] for file */ > static struct nfs4_file * > -find_file(struct inode *ino) > +find_file_locked(struct inode *ino) > { > unsigned int hashval = file_hashval(ino); > struct nfs4_file *fp; > > - spin_lock(&state_lock); > + lockdep_assert_held(&state_lock); > + > hlist_for_each_entry(fp, &file_hashtbl[hashval], fi_hash) { > if (fp->fi_inode == ino) { > get_nfs4_file(fp); > - spin_unlock(&state_lock); > return fp; > } > } > - spin_unlock(&state_lock); > return NULL; > } > > +static struct nfs4_file * > +find_file(struct inode *ino) > +{ > + struct nfs4_file *fp; > + > + spin_lock(&state_lock); > + fp = find_file_locked(ino); > + spin_unlock(&state_lock); > + return fp; > +} > + > +static struct nfs4_file * > +find_or_add_file(struct inode *ino, struct nfs4_file *new) > +{ > + struct nfs4_file *fp; > + > + spin_lock(&state_lock); > + fp = find_file_locked(ino); > + if (fp == NULL) { > + nfsd4_init_file(new, ino); > + fp = new; > + } > + spin_unlock(&state_lock); > + > + return fp; > +} > + > /* > * Called to check deny when READ with all zero stateid or > * WRITE with all zero or all one stateid > @@ -3325,21 +3352,19 @@ nfsd4_process_open2(struct svc_rqst *rqstp, struct svc_fh *current_fh, struct nf > * and check for delegations in the process of being recalled. > * If not found, create the nfs4_file struct > */ > - fp = find_file(ino); > - if (fp) { > + fp = find_or_add_file(ino, open->op_file); > + if (fp != open->op_file) { > if ((status = nfs4_check_open(fp, open, &stp))) > goto out; > status = nfs4_check_deleg(cl, open, &dp); > if (status) > goto out; > } else { > + open->op_file = NULL; > status = nfserr_bad_stateid; > if (nfsd4_is_deleg_cur(open)) > goto out; > status = nfserr_jukebox; > - fp = open->op_file; > - open->op_file = NULL; > - nfsd4_init_file(fp, ino); > } > > /* > -- > 1.9.3 > -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Mon, 30 Jun 2014 16:28:19 -0400 "J. Bruce Fields" <bfields@fieldses.org> wrote: > On Mon, Jun 30, 2014 at 11:48:31AM -0400, Jeff Layton wrote: > > From: Trond Myklebust <trond.myklebust@primarydata.com> > > > > Ensure that we only can have a single struct nfs4_file per inode > > in the file_hashtbl and make addition atomic with respect to lookup. > > This changelog gives the impression it's a bugfix, and it isn't. I > understand it's tedious in this series, but really I think at a minimum > a changelog should always make it clear whether a patch is a bugfix or > not. Applying with changelog rewritten to: > > Current code depends on the client_mutex to guarantee a single > struct nfs4_file per inode in the file_hashtbl and make addition > atomic with respect to lookup. Rely instead on the state_Lock, > to make it easier to stop taking the client_mutex here later. > ... > > --b. > Thanks and sorry, it's definitely correct that it's not a bugfix wrt the existing code. I thought I had updated that patch to spell it out, but I guess I missed that one... > > > > To prevent an i_lock/state_lock inversion, change nfsd4_init_file to > > use ihold instead if igrab. That's also more efficient anyway as we > > definitely hold a reference to the inode at that point. > > > > Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com> > > Signed-off-by: Jeff Layton <jlayton@primarydata.com> > > Reviewed-by: Christoph Hellwig <hch@lst.de> > > --- > > fs/nfsd/nfs4state.c | 49 +++++++++++++++++++++++++++++++++++++------------ > > 1 file changed, 37 insertions(+), 12 deletions(-) > > > > diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c > > index c473bd6d52c8..29788fd0da24 100644 > > --- a/fs/nfsd/nfs4state.c > > +++ b/fs/nfsd/nfs4state.c > > @@ -2611,17 +2611,18 @@ static void nfsd4_init_file(struct nfs4_file *fp, struct inode *ino) > > { > > unsigned int hashval = file_hashval(ino); > > > > + lockdep_assert_held(&state_lock); > > + > > atomic_set(&fp->fi_ref, 1); > > INIT_LIST_HEAD(&fp->fi_stateids); > > INIT_LIST_HEAD(&fp->fi_delegations); > > - fp->fi_inode = igrab(ino); > > + ihold(ino); > > + fp->fi_inode = ino; > > fp->fi_had_conflict = false; > > fp->fi_lease = NULL; > > memset(fp->fi_fds, 0, sizeof(fp->fi_fds)); > > memset(fp->fi_access, 0, sizeof(fp->fi_access)); > > - spin_lock(&state_lock); > > hlist_add_head(&fp->fi_hash, &file_hashtbl[hashval]); > > - spin_unlock(&state_lock); > > } > > > > void > > @@ -2787,23 +2788,49 @@ find_openstateowner_str(unsigned int hashval, struct nfsd4_open *open, > > > > /* search file_hashtbl[] for file */ > > static struct nfs4_file * > > -find_file(struct inode *ino) > > +find_file_locked(struct inode *ino) > > { > > unsigned int hashval = file_hashval(ino); > > struct nfs4_file *fp; > > > > - spin_lock(&state_lock); > > + lockdep_assert_held(&state_lock); > > + > > hlist_for_each_entry(fp, &file_hashtbl[hashval], fi_hash) { > > if (fp->fi_inode == ino) { > > get_nfs4_file(fp); > > - spin_unlock(&state_lock); > > return fp; > > } > > } > > - spin_unlock(&state_lock); > > return NULL; > > } > > > > +static struct nfs4_file * > > +find_file(struct inode *ino) > > +{ > > + struct nfs4_file *fp; > > + > > + spin_lock(&state_lock); > > + fp = find_file_locked(ino); > > + spin_unlock(&state_lock); > > + return fp; > > +} > > + > > +static struct nfs4_file * > > +find_or_add_file(struct inode *ino, struct nfs4_file *new) > > +{ > > + struct nfs4_file *fp; > > + > > + spin_lock(&state_lock); > > + fp = find_file_locked(ino); > > + if (fp == NULL) { > > + nfsd4_init_file(new, ino); > > + fp = new; > > + } > > + spin_unlock(&state_lock); > > + > > + return fp; > > +} > > + > > /* > > * Called to check deny when READ with all zero stateid or > > * WRITE with all zero or all one stateid > > @@ -3325,21 +3352,19 @@ nfsd4_process_open2(struct svc_rqst *rqstp, struct svc_fh *current_fh, struct nf > > * and check for delegations in the process of being recalled. > > * If not found, create the nfs4_file struct > > */ > > - fp = find_file(ino); > > - if (fp) { > > + fp = find_or_add_file(ino, open->op_file); > > + if (fp != open->op_file) { > > if ((status = nfs4_check_open(fp, open, &stp))) > > goto out; > > status = nfs4_check_deleg(cl, open, &dp); > > if (status) > > goto out; > > } else { > > + open->op_file = NULL; > > status = nfserr_bad_stateid; > > if (nfsd4_is_deleg_cur(open)) > > goto out; > > status = nfserr_jukebox; > > - fp = open->op_file; > > - open->op_file = NULL; > > - nfsd4_init_file(fp, ino); > > } > > > > /* > > -- > > 1.9.3 > >
diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c index c473bd6d52c8..29788fd0da24 100644 --- a/fs/nfsd/nfs4state.c +++ b/fs/nfsd/nfs4state.c @@ -2611,17 +2611,18 @@ static void nfsd4_init_file(struct nfs4_file *fp, struct inode *ino) { unsigned int hashval = file_hashval(ino); + lockdep_assert_held(&state_lock); + atomic_set(&fp->fi_ref, 1); INIT_LIST_HEAD(&fp->fi_stateids); INIT_LIST_HEAD(&fp->fi_delegations); - fp->fi_inode = igrab(ino); + ihold(ino); + fp->fi_inode = ino; fp->fi_had_conflict = false; fp->fi_lease = NULL; memset(fp->fi_fds, 0, sizeof(fp->fi_fds)); memset(fp->fi_access, 0, sizeof(fp->fi_access)); - spin_lock(&state_lock); hlist_add_head(&fp->fi_hash, &file_hashtbl[hashval]); - spin_unlock(&state_lock); } void @@ -2787,23 +2788,49 @@ find_openstateowner_str(unsigned int hashval, struct nfsd4_open *open, /* search file_hashtbl[] for file */ static struct nfs4_file * -find_file(struct inode *ino) +find_file_locked(struct inode *ino) { unsigned int hashval = file_hashval(ino); struct nfs4_file *fp; - spin_lock(&state_lock); + lockdep_assert_held(&state_lock); + hlist_for_each_entry(fp, &file_hashtbl[hashval], fi_hash) { if (fp->fi_inode == ino) { get_nfs4_file(fp); - spin_unlock(&state_lock); return fp; } } - spin_unlock(&state_lock); return NULL; } +static struct nfs4_file * +find_file(struct inode *ino) +{ + struct nfs4_file *fp; + + spin_lock(&state_lock); + fp = find_file_locked(ino); + spin_unlock(&state_lock); + return fp; +} + +static struct nfs4_file * +find_or_add_file(struct inode *ino, struct nfs4_file *new) +{ + struct nfs4_file *fp; + + spin_lock(&state_lock); + fp = find_file_locked(ino); + if (fp == NULL) { + nfsd4_init_file(new, ino); + fp = new; + } + spin_unlock(&state_lock); + + return fp; +} + /* * Called to check deny when READ with all zero stateid or * WRITE with all zero or all one stateid @@ -3325,21 +3352,19 @@ nfsd4_process_open2(struct svc_rqst *rqstp, struct svc_fh *current_fh, struct nf * and check for delegations in the process of being recalled. * If not found, create the nfs4_file struct */ - fp = find_file(ino); - if (fp) { + fp = find_or_add_file(ino, open->op_file); + if (fp != open->op_file) { if ((status = nfs4_check_open(fp, open, &stp))) goto out; status = nfs4_check_deleg(cl, open, &dp); if (status) goto out; } else { + open->op_file = NULL; status = nfserr_bad_stateid; if (nfsd4_is_deleg_cur(open)) goto out; status = nfserr_jukebox; - fp = open->op_file; - open->op_file = NULL; - nfsd4_init_file(fp, ino); } /*