[PATCH 05/19] nfsd: Push mnt_want_write() outside of i_mutex

From: Jan Kara
Date: Mon Mar 05 2012 - 11:08:13 EST

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When mnt_want_write() starts to handle freezing it will get a full lock
semantics requiring proper lock ordering. So push mnt_want_write() call
consistently outside of i_mutex.

CC: linux-nfs@xxxxxxxxxxxxxxx
CC: "J. Bruce Fields" <bfields@xxxxxxxxxxxx>
Signed-off-by: Jan Kara <jack@xxxxxxx>
---
fs/nfsd/nfs4recover.c | 9 +++--
fs/nfsd/nfsfh.c | 1 +
fs/nfsd/nfsproc.c | 9 ++++-
fs/nfsd/vfs.c | 79 ++++++++++++++++++++++---------------------
fs/nfsd/vfs.h | 11 +++++-
include/linux/nfsd/nfsfh.h | 1 +
6 files changed, 64 insertions(+), 46 deletions(-)

diff --git a/fs/nfsd/nfs4recover.c b/fs/nfsd/nfs4recover.c
index 0b3e875..8e599a6 100644
--- a/fs/nfsd/nfs4recover.c
+++ b/fs/nfsd/nfs4recover.c
@@ -135,6 +135,10 @@ void nfsd4_create_clid_dir(struct nfs4_client *clp)
if (status < 0)
return;

+ status = mnt_want_write_file(rec_file);
+ if (status)
+ return;
+
dir = rec_file->f_path.dentry;
/* lock the parent */
mutex_lock(&dir->d_inode->i_mutex);
@@ -154,11 +158,7 @@ void nfsd4_create_clid_dir(struct nfs4_client *clp)
* as well be forgiving and just succeed silently.
*/
goto out_put;
- status = mnt_want_write_file(rec_file);
- if (status)
- goto out_put;
status = vfs_mkdir(dir->d_inode, dentry, S_IRWXU);
- mnt_drop_write_file(rec_file);
out_put:
dput(dentry);
out_unlock:
@@ -170,6 +170,7 @@ out_unlock:
" (err %d); please check that %s exists"
" and is writeable", status,
user_recovery_dirname);
+ mnt_drop_write_file(rec_file);
nfs4_reset_creds(original_cred);
}

diff --git a/fs/nfsd/nfsfh.c b/fs/nfsd/nfsfh.c
index 68454e7..8b93353 100644
--- a/fs/nfsd/nfsfh.c
+++ b/fs/nfsd/nfsfh.c
@@ -635,6 +635,7 @@ fh_put(struct svc_fh *fhp)
fhp->fh_post_saved = 0;
#endif
}
+ fh_drop_write(fhp);
if (exp) {
cache_put(&exp->h, &svc_export_cache);
fhp->fh_export = NULL;
diff --git a/fs/nfsd/nfsproc.c b/fs/nfsd/nfsproc.c
index e15dc45..aad6d45 100644
--- a/fs/nfsd/nfsproc.c
+++ b/fs/nfsd/nfsproc.c
@@ -196,6 +196,7 @@ nfsd_proc_create(struct svc_rqst *rqstp, struct nfsd_createargs *argp,
struct dentry *dchild;
int type, mode;
__be32 nfserr;
+ int hosterr;
dev_t rdev = 0, wanted = new_decode_dev(attr->ia_size);

dprintk("nfsd: CREATE %s %.*s\n",
@@ -214,6 +215,12 @@ nfsd_proc_create(struct svc_rqst *rqstp, struct nfsd_createargs *argp,
nfserr = nfserr_exist;
if (isdotent(argp->name, argp->len))
goto done;
+ hosterr = fh_want_write(dirfhp);
+ if (hosterr) {
+ nfserr = nfserrno(hosterr);
+ goto done;
+ }
+
fh_lock_nested(dirfhp, I_MUTEX_PARENT);
dchild = lookup_one_len(argp->name, dirfhp->fh_dentry, argp->len);
if (IS_ERR(dchild)) {
@@ -330,7 +337,7 @@ nfsd_proc_create(struct svc_rqst *rqstp, struct nfsd_createargs *argp,
out_unlock:
/* We don't really need to unlock, as fh_put does it. */
fh_unlock(dirfhp);
-
+ fh_drop_write(dirfhp);
done:
fh_put(dirfhp);
return nfsd_return_dirop(nfserr, resp);
diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
index edf6d3e..af49c63 100644
--- a/fs/nfsd/vfs.c
+++ b/fs/nfsd/vfs.c
@@ -1268,6 +1268,10 @@ nfsd_create(struct svc_rqst *rqstp, struct svc_fh *fhp,
* If it has, the parent directory should already be locked.
*/
if (!resfhp->fh_dentry) {
+ host_err = fh_want_write(fhp);
+ if (host_err)
+ goto out_nfserr;
+
/* called from nfsd_proc_mkdir, or possibly nfsd3_proc_create */
fh_lock_nested(fhp, I_MUTEX_PARENT);
dchild = lookup_one_len(fname, dentry, flen);
@@ -1311,14 +1315,11 @@ nfsd_create(struct svc_rqst *rqstp, struct svc_fh *fhp,
goto out;
}

- host_err = fh_want_write(fhp);
- if (host_err)
- goto out_nfserr;
-
/*
* Get the dir op function pointer.
*/
err = 0;
+ host_err = 0;
switch (type) {
case S_IFREG:
host_err = vfs_create(dirp, dchild, iap->ia_mode, NULL);
@@ -1335,10 +1336,8 @@ nfsd_create(struct svc_rqst *rqstp, struct svc_fh *fhp,
host_err = vfs_mknod(dirp, dchild, iap->ia_mode, rdev);
break;
}
- if (host_err < 0) {
- fh_drop_write(fhp);
+ if (host_err < 0)
goto out_nfserr;
- }

err = nfsd_create_setattr(rqstp, resfhp, iap);

@@ -1350,7 +1349,6 @@ nfsd_create(struct svc_rqst *rqstp, struct svc_fh *fhp,
err2 = nfserrno(commit_metadata(fhp));
if (err2)
err = err2;
- fh_drop_write(fhp);
/*
* Update the file handle to get the new inode info.
*/
@@ -1409,6 +1407,11 @@ do_nfsd_create(struct svc_rqst *rqstp, struct svc_fh *fhp,
err = nfserr_notdir;
if (!dirp->i_op->lookup)
goto out;
+
+ host_err = fh_want_write(fhp);
+ if (host_err)
+ goto out_nfserr;
+
fh_lock_nested(fhp, I_MUTEX_PARENT);

/*
@@ -1441,9 +1444,6 @@ do_nfsd_create(struct svc_rqst *rqstp, struct svc_fh *fhp,
v_atime = verifier[1]&0x7fffffff;
}

- host_err = fh_want_write(fhp);
- if (host_err)
- goto out_nfserr;
if (dchild->d_inode) {
err = 0;

@@ -1514,7 +1514,6 @@ do_nfsd_create(struct svc_rqst *rqstp, struct svc_fh *fhp,
if (!err)
err = nfserrno(commit_metadata(fhp));

- fh_drop_write(fhp);
/*
* Update the filehandle to get the new inode info.
*/
@@ -1525,6 +1524,7 @@ do_nfsd_create(struct svc_rqst *rqstp, struct svc_fh *fhp,
fh_unlock(fhp);
if (dchild && !IS_ERR(dchild))
dput(dchild);
+ fh_drop_write(fhp);
return err;

out_nfserr:
@@ -1604,6 +1604,11 @@ nfsd_symlink(struct svc_rqst *rqstp, struct svc_fh *fhp,
err = fh_verify(rqstp, fhp, S_IFDIR, NFSD_MAY_CREATE);
if (err)
goto out;
+
+ host_err = fh_want_write(fhp);
+ if (host_err)
+ goto out_nfserr;
+
fh_lock(fhp);
dentry = fhp->fh_dentry;
dnew = lookup_one_len(fname, dentry, flen);
@@ -1611,10 +1616,6 @@ nfsd_symlink(struct svc_rqst *rqstp, struct svc_fh *fhp,
if (IS_ERR(dnew))
goto out_nfserr;

- host_err = fh_want_write(fhp);
- if (host_err)
- goto out_nfserr;
-
if (unlikely(path[plen] != 0)) {
char *path_alloced = kmalloc(plen+1, GFP_KERNEL);
if (path_alloced == NULL)
@@ -1674,6 +1675,12 @@ nfsd_link(struct svc_rqst *rqstp, struct svc_fh *ffhp,
if (isdotent(name, len))
goto out;

+ host_err = fh_want_write(tfhp);
+ if (host_err) {
+ err = nfserrno(host_err);
+ goto out;
+ }
+
fh_lock_nested(ffhp, I_MUTEX_PARENT);
ddir = ffhp->fh_dentry;
dirp = ddir->d_inode;
@@ -1685,18 +1692,13 @@ nfsd_link(struct svc_rqst *rqstp, struct svc_fh *ffhp,

dold = tfhp->fh_dentry;

- host_err = fh_want_write(tfhp);
- if (host_err) {
- err = nfserrno(host_err);
- goto out_dput;
- }
err = nfserr_noent;
if (!dold->d_inode)
- goto out_drop_write;
+ goto out_dput;
host_err = nfsd_break_lease(dold->d_inode);
if (host_err) {
err = nfserrno(host_err);
- goto out_drop_write;
+ goto out_dput;
}
host_err = vfs_link(dold, dirp, dnew);
if (!host_err) {
@@ -1709,12 +1711,11 @@ nfsd_link(struct svc_rqst *rqstp, struct svc_fh *ffhp,
else
err = nfserrno(host_err);
}
-out_drop_write:
- fh_drop_write(tfhp);
out_dput:
dput(dnew);
out_unlock:
fh_unlock(ffhp);
+ fh_drop_write(tfhp);
out:
return err;

@@ -1757,6 +1758,12 @@ nfsd_rename(struct svc_rqst *rqstp, struct svc_fh *ffhp, char *fname, int flen,
if (!flen || isdotent(fname, flen) || !tlen || isdotent(tname, tlen))
goto out;

+ host_err = fh_want_write(ffhp);
+ if (host_err) {
+ err = nfserrno(host_err);
+ goto out;
+ }
+
/* cannot use fh_lock as we need deadlock protective ordering
* so do it by hand */
trap = lock_rename(tdentry, fdentry);
@@ -1787,17 +1794,14 @@ nfsd_rename(struct svc_rqst *rqstp, struct svc_fh *ffhp, char *fname, int flen,
host_err = -EXDEV;
if (ffhp->fh_export->ex_path.mnt != tfhp->fh_export->ex_path.mnt)
goto out_dput_new;
- host_err = fh_want_write(ffhp);
- if (host_err)
- goto out_dput_new;

host_err = nfsd_break_lease(odentry->d_inode);
if (host_err)
- goto out_drop_write;
+ goto out_dput_new;
if (ndentry->d_inode) {
host_err = nfsd_break_lease(ndentry->d_inode);
if (host_err)
- goto out_drop_write;
+ goto out_dput_new;
}
host_err = vfs_rename(fdir, odentry, tdir, ndentry);
if (!host_err) {
@@ -1805,8 +1809,6 @@ nfsd_rename(struct svc_rqst *rqstp, struct svc_fh *ffhp, char *fname, int flen,
if (!host_err)
host_err = commit_metadata(ffhp);
}
-out_drop_write:
- fh_drop_write(ffhp);
out_dput_new:
dput(ndentry);
out_dput_old:
@@ -1822,6 +1824,7 @@ out_drop_write:
fill_post_wcc(tfhp);
unlock_rename(tdentry, fdentry);
ffhp->fh_locked = tfhp->fh_locked = 0;
+ fh_drop_write(ffhp);

out:
return err;
@@ -1847,6 +1850,10 @@ nfsd_unlink(struct svc_rqst *rqstp, struct svc_fh *fhp, int type,
if (err)
goto out;

+ host_err = fh_want_write(fhp);
+ if (host_err)
+ goto out_nfserr;
+
fh_lock_nested(fhp, I_MUTEX_PARENT);
dentry = fhp->fh_dentry;
dirp = dentry->d_inode;
@@ -1865,21 +1872,15 @@ nfsd_unlink(struct svc_rqst *rqstp, struct svc_fh *fhp, int type,
if (!type)
type = rdentry->d_inode->i_mode & S_IFMT;

- host_err = fh_want_write(fhp);
- if (host_err)
- goto out_put;
-
host_err = nfsd_break_lease(rdentry->d_inode);
if (host_err)
- goto out_drop_write;
+ goto out_put;
if (type != S_IFDIR)
host_err = vfs_unlink(dirp, rdentry);
else
host_err = vfs_rmdir(dirp, rdentry);
if (!host_err)
host_err = commit_metadata(fhp);
-out_drop_write:
- fh_drop_write(fhp);
out_put:
dput(rdentry);

diff --git a/fs/nfsd/vfs.h b/fs/nfsd/vfs.h
index 1dcd238..d5a50b4 100644
--- a/fs/nfsd/vfs.h
+++ b/fs/nfsd/vfs.h
@@ -108,12 +108,19 @@ int nfsd_set_posix_acl(struct svc_fh *, int, struct posix_acl *);

static inline int fh_want_write(struct svc_fh *fh)
{
- return mnt_want_write(fh->fh_export->ex_path.mnt);
+ int ret = mnt_want_write(fh->fh_export->ex_path.mnt);
+
+ if (!ret)
+ fh->fh_want_write = 1;
+ return ret;
}

static inline void fh_drop_write(struct svc_fh *fh)
{
- mnt_drop_write(fh->fh_export->ex_path.mnt);
+ if (fh->fh_want_write) {
+ fh->fh_want_write = 0;
+ mnt_drop_write(fh->fh_export->ex_path.mnt);
+ }
}

#endif /* LINUX_NFSD_VFS_H */
diff --git a/include/linux/nfsd/nfsfh.h b/include/linux/nfsd/nfsfh.h
index ce4743a..fa63048 100644
--- a/include/linux/nfsd/nfsfh.h
+++ b/include/linux/nfsd/nfsfh.h
@@ -143,6 +143,7 @@ typedef struct svc_fh {
int fh_maxsize; /* max size for fh_handle */

unsigned char fh_locked; /* inode locked by us */
+ unsigned char fh_want_write; /* remount protection taken */

#ifdef CONFIG_NFSD_V3
unsigned char fh_post_saved; /* post-op attrs saved */
--
1.7.1

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Next message: Jan Kara: "[PATCH 01/19] mm: Make default vm_ops provide ->page_mkwrite handler"
Previous message: Jan Kara: "[PATCH 06/19] fs: Improve filesystem freezing handling"
In reply to: Jan Kara: "[PATCH 06/19] fs: Improve filesystem freezing handling"
Next in thread: Jan Kara: "[PATCH 01/19] mm: Make default vm_ops provide ->page_mkwrite handler"
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