[uml-devel] [PATCH] Make hostfs_setattr() support operations on closed files.

[uml-devel] [PATCH] Make hostfs_setattr() support operations on closed files.

[Alberto Bertogli]

This patch allows hostfs_setattr() to work on closed files by calling
set_attr() (the userspace part) with the inode's fd.

Without this, applications that depend on doing attribute changes to
closed files will fail.

It works by using the fd versions instead of the path ones (for example
fchmod() instead of chmod(), fchown() instead of chown()) when an fd is
available.


Signed-off-by: Alberto Bertogli <albertito@gmail.com>
---

I hit this using hostfs as my root device and trying to do dpkg-reconfigure
locales, which called locale-gen which did something like:

	fd = open("f1.tmp");
	write(fd, ...);
	link("f1.tmp", "f1");
	unlink("f1.tmp");
	fchmod(fd, 0644);

And fchmod failed with ENOENT.

I compiled this and tested with locale-gen and a testcase I wrote for this.

I was also worried about the semantics, for instance, the outcome of:

	fd = open("f1.tmp");
	write(fd, ...);
	link("f1.tmp", "f1");
	unlink("f1.tmp");
	fd2 = open("f1.tmp");
	fchmod(fd, 0644);

In the host fchmod() changes f1 and not f1.tmp, but maybe the open() in the
middle got hostfs confused. Luckily this is not the case and it works fine;
but as I'm not familiar with hostfs there may be other issues.


 fs/hostfs/hostfs.h      |    4 +-
 fs/hostfs/hostfs_kern.c |   10 ++++-
 fs/hostfs/hostfs_user.c |   89 ++++++++++++++++++++++++++++++++++++++++-------
 3 files changed, 86 insertions(+), 17 deletions(-)

diff --git a/fs/hostfs/hostfs.h b/fs/hostfs/hostfs.h
index 70543b1..d8850c7 100644
--- a/fs/hostfs/hostfs.h
+++ b/fs/hostfs/hostfs.h
@@ -55,7 +55,7 @@ extern int stat_file(const char *path, unsigned long long *inode_out,
 		     int *mode_out, int *nlink_out, int *uid_out, int *gid_out,
 		     unsigned long long *size_out, struct timespec *atime_out,
 		     struct timespec *mtime_out, struct timespec *ctime_out,
-		     int *blksize_out, unsigned long long *blocks_out);
+		     int *blksize_out, unsigned long long *blocks_out, int fd);
 extern int access_file(char *path, int r, int w, int x);
 extern int open_file(char *path, int r, int w, int append);
 extern int file_type(const char *path, int *maj, int *min);
@@ -71,7 +71,7 @@ extern int lseek_file(int fd, long long offset, int whence);
 extern int fsync_file(int fd, int datasync);
 extern int file_create(char *name, int ur, int uw, int ux, int gr,
 		       int gw, int gx, int or, int ow, int ox);
-extern int set_attr(const char *file, struct hostfs_iattr *attrs);
+extern int set_attr(const char *file, struct hostfs_iattr *attrs, int fd);
 extern int make_symlink(const char *from, const char *to);
 extern int unlink_file(const char *file);
 extern int do_mkdir(const char *file, int mode);
diff --git a/fs/hostfs/hostfs_kern.c b/fs/hostfs/hostfs_kern.c
index fd301a9..c704d9c 100644
--- a/fs/hostfs/hostfs_kern.c
+++ b/fs/hostfs/hostfs_kern.c
@@ -147,7 +147,7 @@ static int read_name(struct inode *ino, char *name)
 
 	err = stat_file(name, &i_ino, &i_mode, &i_nlink, &ino->i_uid,
 			&ino->i_gid, &i_size, &ino->i_atime, &ino->i_mtime,
-			&ino->i_ctime, &i_blksize, &i_blocks);
+			&ino->i_ctime, &i_blksize, &i_blocks, -1);
 	if(err)
 		return(err);
 
@@ -817,8 +817,14 @@ int hostfs_permission(struct inode *ino, int desired, struct nameidata *nd)
 int hostfs_setattr(struct dentry *dentry, struct iattr *attr)
 {
 	struct hostfs_iattr attrs;
+	struct hostfs_inode_info *iinfo;
 	char *name;
 	int err;
+	int fd = -1;
+
+	iinfo = HOSTFS_I(dentry->d_inode);
+	if (iinfo != NULL)
+		fd = iinfo->fd;
 
 	err = inode_change_ok(dentry->d_inode, attr);
 	if (err)
@@ -864,7 +870,7 @@ int hostfs_setattr(struct dentry *dentry, struct iattr *attr)
 	}
 	name = dentry_name(dentry, 0);
 	if(name == NULL) return(-ENOMEM);
-	err = set_attr(name, &attrs);
+	err = set_attr(name, &attrs, fd);
 	kfree(name);
 	if(err)
 		return(err);
diff --git a/fs/hostfs/hostfs_user.c b/fs/hostfs/hostfs_user.c
index 1ed5ea3..e3b4d7c 100644
--- a/fs/hostfs/hostfs_user.c
+++ b/fs/hostfs/hostfs_user.c
@@ -21,12 +21,16 @@ int stat_file(const char *path, unsigned long long *inode_out, int *mode_out,
 	      int *nlink_out, int *uid_out, int *gid_out,
 	      unsigned long long *size_out, struct timespec *atime_out,
 	      struct timespec *mtime_out, struct timespec *ctime_out,
-	      int *blksize_out, unsigned long long *blocks_out)
+	      int *blksize_out, unsigned long long *blocks_out, int fd)
 {
 	struct stat64 buf;
 
-	if(lstat64(path, &buf) < 0)
+	if(fd >= 0) {
+		if (fstat64(fd, &buf) < 0)
+			return(-errno);
+	} else if(lstat64(path, &buf) < 0) {
 		return(-errno);
+	}
 
 	if(inode_out != NULL) *inode_out = buf.st_ino;
 	if(mode_out != NULL) *mode_out = buf.st_mode;
@@ -202,58 +206,117 @@ int file_create(char *name, int ur, int uw, int ux, int gr,
 	return(fd);
 }
 
-int set_attr(const char *file, struct hostfs_iattr *attrs)
+int set_attr(const char *file, struct hostfs_iattr *attrs, int fd)
 {
 	struct utimbuf buf;
 	int err, ma;
 
 	if(attrs->ia_valid & HOSTFS_ATTR_MODE){
-		if(chmod(file, attrs->ia_mode) != 0) return(-errno);
+		if(fd >= 0){
+			if(fchmod(fd, attrs->ia_mode) != 0) return(-errno);
+		} else if(chmod(file, attrs->ia_mode) != 0){
+			return(-errno);
+		}
 	}
 	if(attrs->ia_valid & HOSTFS_ATTR_UID){
-		if(chown(file, attrs->ia_uid, -1)) return(-errno);
+		if(fd >= 0) {
+			if (fchown(fd, attrs->ia_uid, -1)) return(-errno);
+		} else if(chown(file, attrs->ia_uid, -1)){
+			return(-errno);
+		}
 	}
 	if(attrs->ia_valid & HOSTFS_ATTR_GID){
-		if(chown(file, -1, attrs->ia_gid)) return(-errno);
+		if(fd >= 0){
+			if (fchown(fd, -1, attrs->ia_gid)) return(-errno);
+		} else if(chown(file, -1, attrs->ia_gid)){
+			return(-errno);
+		}
 	}
 	if(attrs->ia_valid & HOSTFS_ATTR_SIZE){
-		if(truncate(file, attrs->ia_size)) return(-errno);
+		if(fd >= 0){
+			if (ftruncate(fd, attrs->ia_size)) return(-errno);
+		} else if(truncate(file, attrs->ia_size)) {
+			return(-errno);
+		}
 	}
 	ma = HOSTFS_ATTR_ATIME_SET | HOSTFS_ATTR_MTIME_SET;
 	if((attrs->ia_valid & ma) == ma){
+		struct timeval times[2];
+
 		buf.actime = attrs->ia_atime.tv_sec;
 		buf.modtime = attrs->ia_mtime.tv_sec;
-		if(utime(file, &buf) != 0) return(-errno);
+
+		/* atime */
+		times[0].tv_sec = attrs->ia_atime.tv_sec;
+		times[0].tv_usec = attrs->ia_atime.tv_nsec * 1000;
+
+		/* mtime */
+		times[1].tv_sec = attrs->ia_mtime.tv_sec;
+		times[1].tv_usec = attrs->ia_mtime.tv_nsec * 1000;
+
+		if(fd >= 0){
+			if(futimes(fd, times) != 0)
+				return(-errno);
+		} else if(utime(file, &buf) != 0){
+			return(-errno);
+		}
 	}
 	else {
 		struct timespec ts;
+		struct timeval times[2];
 
 		if(attrs->ia_valid & HOSTFS_ATTR_ATIME_SET){
 			err = stat_file(file, NULL, NULL, NULL, NULL, NULL,
-					NULL, NULL, &ts, NULL, NULL, NULL);
+					NULL, NULL, &ts, NULL, NULL, NULL, fd);
 			if(err != 0)
 				return(err);
 			buf.actime = attrs->ia_atime.tv_sec;
 			buf.modtime = ts.tv_sec;
-			if(utime(file, &buf) != 0)
+
+			/* atime */
+			times[0].tv_sec = attrs->ia_atime.tv_sec;
+			times[0].tv_usec = attrs->ia_atime.tv_nsec * 1000;
+
+			/* mtime */
+			times[1].tv_sec = ts.tv_sec;
+			times[1].tv_usec = ts.tv_nsec * 1000;
+
+			if(fd >= 0){
+				if(futimes(fd, times) != 0)
+					return(-errno);
+			} else if(utime(file, &buf) != 0){
 				return(-errno);
+			}
 		}
 		if(attrs->ia_valid & HOSTFS_ATTR_MTIME_SET){
 			err = stat_file(file, NULL, NULL, NULL, NULL, NULL,
-					NULL, &ts, NULL, NULL, NULL, NULL);
+					NULL, &ts, NULL, NULL, NULL, NULL, fd);
 			if(err != 0)
 				return(err);
 			buf.actime = ts.tv_sec;
 			buf.modtime = attrs->ia_mtime.tv_sec;
-			if(utime(file, &buf) != 0)
+
+			/* atime */
+			times[0].tv_sec = ts.tv_sec;
+			times[0].tv_usec = ts.tv_nsec * 1000;
+
+			/* mtime */
+			times[1].tv_sec = attrs->ia_mtime.tv_sec;
+			times[1].tv_usec = attrs->ia_mtime.tv_nsec * 1000;
+
+			if(fd >= 0){
+				if(futimes(fd, times) != 0)
+					return(-errno);
+			} else if(utime(file, &buf) != 0){
 				return(-errno);
+			}
 		}
 	}
 	if(attrs->ia_valid & HOSTFS_ATTR_CTIME) ;
 	if(attrs->ia_valid & (HOSTFS_ATTR_ATIME | HOSTFS_ATTR_MTIME)){
 		err = stat_file(file, NULL, NULL, NULL, NULL, NULL, NULL,
 				&attrs->ia_atime, &attrs->ia_mtime, NULL,
-				NULL, NULL);
+				NULL, NULL, fd);
 		if(err != 0) return(err);
 	}
 	return(0);
-- 
1.5.1.1


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Re: [uml-devel] [PATCH] Make hostfs_setattr() support operations on closed files.

[Blaisorblade]

On martedì 24 aprile 2007, Alberto Bertogli wrote:
> This patch allows hostfs_setattr() to work on closed files by calling
> set_attr() (the userspace part) with the inode's fd.
>
> Without this, applications that depend on doing attribute changes to
> closed files will fail.
>
> It works by using the fd versions instead of the path ones (for example
> fchmod() instead of chmod(), fchown() instead of chown()) when an fd is
> available.
>
>
> Signed-off-by: Alberto Bertogli <albertito@gmail.com>
> ---
This makes sense and is useful - but:
1) when I read the examples, I understood you meant 'unlinked open files', 
not 'closed files'. Right?

The patch is of good quality; I've not seen any single bug, which is rare in 
such submission, but before merging, some little things should be fixed up 
(either by you or by Jeff).

2) if (...) return ...; on a single line is horrible style, should be 
corrected (I see sometimes the original code uses it, well it shouldn't).

> I was also worried about the semantics, for instance, the outcome of:
>
> 	fd = open("f1.tmp");
> 	write(fd, ...);
> 	link("f1.tmp", "f1");
> 	unlink("f1.tmp");
> 	fd2 = open("f1.tmp");
> 	fchmod(fd, 0644);

> In the host fchmod() changes f1 and not f1.tmp, but maybe the open() in the
> middle got hostfs confused. Luckily this is not the case and it works fine;
> but as I'm not familiar with hostfs there may be other issues.

I guess the patch would make this work, right?

> diff --git a/fs/hostfs/hostfs_kern.c b/fs/hostfs/hostfs_kern.c
> index fd301a9..c704d9c 100644

> @@ -817,8 +817,14 @@ int hostfs_permission(struct inode *ino, int desired,
> struct nameidata *nd) int hostfs_setattr(struct dentry *dentry, struct
> iattr *attr)
>  {
>  	struct hostfs_iattr attrs;
> +	struct hostfs_inode_info *iinfo;
>  	char *name;
>  	int err;
> +	int fd = -1;
> +
> +	iinfo = HOSTFS_I(dentry->d_inode);
> +	if (iinfo != NULL)
> +		fd = iinfo->fd;

iinfo cannot be NULL, so please remove that if. HOSTFS_I does not access a 
field of d_inode; rather, d_inode points to a field of iinfo, i.e. the 
vfs_inode field of struct hostfs_inode_info.

>  	err = inode_change_ok(dentry->d_inode, attr);
>  	if (err)
> @@ -864,7 +870,7 @@ int hostfs_setattr(struct dentry *dentry, struct iattr
> *attr) }
>  	name = dentry_name(dentry, 0);
>  	if(name == NULL) return(-ENOMEM);
> -	err = set_attr(name, &attrs);
> +	err = set_attr(name, &attrs, fd);
>  	kfree(name);
>  	if(err)
>  		return(err);

I do not like the below code. The different code is for setting buf; what 
follows that is common to all cases, and the conversion probably should be 
factored out into a conversion function for better clarity: verifying what 
the code does is difficult here.

>  	ma = HOSTFS_ATTR_ATIME_SET | HOSTFS_ATTR_MTIME_SET;
>  	if((attrs->ia_valid & ma) == ma){
> +		struct timeval times[2];
> +
>  		buf.actime = attrs->ia_atime.tv_sec;
>  		buf.modtime = attrs->ia_mtime.tv_sec;
> -		if(utime(file, &buf) != 0) return(-errno);
> +
> +		/* atime */
> +		times[0].tv_sec = attrs->ia_atime.tv_sec;
> +		times[0].tv_usec = attrs->ia_atime.tv_nsec * 1000;
> +
> +		/* mtime */
> +		times[1].tv_sec = attrs->ia_mtime.tv_sec;
> +		times[1].tv_usec = attrs->ia_mtime.tv_nsec * 1000;
> +
> +		if(fd >= 0){
> +			if(futimes(fd, times) != 0)
> +				return(-errno);
> +		} else if(utime(file, &buf) != 0){
> +			return(-errno);
> +		}
>  	}
>  	else {
>  		struct timespec ts;
> +		struct timeval times[2];
>
>  		if(attrs->ia_valid & HOSTFS_ATTR_ATIME_SET){
>  			err = stat_file(file, NULL, NULL, NULL, NULL, NULL,
> -					NULL, NULL, &ts, NULL, NULL, NULL);
> +					NULL, NULL, &ts, NULL, NULL, NULL, fd);
>  			if(err != 0)
>  				return(err);
>  			buf.actime = attrs->ia_atime.tv_sec;
>  			buf.modtime = ts.tv_sec;
> -			if(utime(file, &buf) != 0)
> +
> +			/* atime */
> +			times[0].tv_sec = attrs->ia_atime.tv_sec;
> +			times[0].tv_usec = attrs->ia_atime.tv_nsec * 1000;
> +
> +			/* mtime */
> +			times[1].tv_sec = ts.tv_sec;
> +			times[1].tv_usec = ts.tv_nsec * 1000;
> +
> +			if(fd >= 0){
> +				if(futimes(fd, times) != 0)
> +					return(-errno);
> +			} else if(utime(file, &buf) != 0){
>  				return(-errno);
> +			}
>  		}
>  		if(attrs->ia_valid & HOSTFS_ATTR_MTIME_SET){
>  			err = stat_file(file, NULL, NULL, NULL, NULL, NULL,
> -					NULL, &ts, NULL, NULL, NULL, NULL);
> +					NULL, &ts, NULL, NULL, NULL, NULL, fd);
>  			if(err != 0)
>  				return(err);
>  			buf.actime = ts.tv_sec;
>  			buf.modtime = attrs->ia_mtime.tv_sec;
> -			if(utime(file, &buf) != 0)
> +
> +			/* atime */
> +			times[0].tv_sec = ts.tv_sec;
> +			times[0].tv_usec = ts.tv_nsec * 1000;
> +
> +			/* mtime */
> +			times[1].tv_sec = attrs->ia_mtime.tv_sec;
> +			times[1].tv_usec = attrs->ia_mtime.tv_nsec * 1000;
> +
> +			if(fd >= 0){
> +				if(futimes(fd, times) != 0)
> +					return(-errno);
> +			} else if(utime(file, &buf) != 0){
>  				return(-errno);
> +			}
>  		}
>  	}
>  	if(attrs->ia_valid & HOSTFS_ATTR_CTIME) ;
>  	if(attrs->ia_valid & (HOSTFS_ATTR_ATIME | HOSTFS_ATTR_MTIME)){
>  		err = stat_file(file, NULL, NULL, NULL, NULL, NULL, NULL,
>  				&attrs->ia_atime, &attrs->ia_mtime, NULL,
> -				NULL, NULL);
> +				NULL, NULL, fd);
>  		if(err != 0) return(err);
>  	}
>  	return(0);



-- 
Inform me of my mistakes, so I can add them to my list!
Paolo Giarrusso, aka Blaisorblade
http://www.user-mode-linux.org/~blaisorblade

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Re: [uml-devel] [PATCH] Make hostfs_setattr() support operations on closed files.

[Alberto Bertogli]

On Wed, Apr 25, 2007 at 05:51:10PM +0200, Blaisorblade wrote:
> On martedì 24 aprile 2007, Alberto Bertogli wrote:
> > This patch allows hostfs_setattr() to work on closed files by calling
> > set_attr() (the userspace part) with the inode's fd.
> >
> > Without this, applications that depend on doing attribute changes to
> > closed files will fail.
> >
> > It works by using the fd versions instead of the path ones (for example
> > fchmod() instead of chmod(), fchown() instead of chown()) when an fd is
> > available.
> >
> >
> > Signed-off-by: Alberto Bertogli <albertito@gmail.com>
> > ---
> This makes sense and is useful - but:
> 1) when I read the examples, I understood you meant 'unlinked open files', 
> not 'closed files'. Right?

Right, sorry about that, the terminology I used is completely
misleading. I'll change the description.


> The patch is of good quality; I've not seen any single bug, which is rare in 
> such submission, but before merging, some little things should be fixed up 
> (either by you or by Jeff).
> 
> 2) if (...) return ...; on a single line is horrible style, should be 
> corrected (I see sometimes the original code uses it, well it shouldn't).

I couldn't agree more. I did it that way because I tried to follow the
coding style of the original code.


> > In the host fchmod() changes f1 and not f1.tmp, but maybe the open() in the
> > middle got hostfs confused. Luckily this is not the case and it works fine;
> > but as I'm not familiar with hostfs there may be other issues.
> 
> I guess the patch would make this work, right?

Yes, that case works with the patch.


> > diff --git a/fs/hostfs/hostfs_kern.c b/fs/hostfs/hostfs_kern.c
> > index fd301a9..c704d9c 100644
> 
> > @@ -817,8 +817,14 @@ int hostfs_permission(struct inode *ino, int desired,
> > struct nameidata *nd) int hostfs_setattr(struct dentry *dentry, struct
> > iattr *attr)
> >  {
> >  	struct hostfs_iattr attrs;
> > +	struct hostfs_inode_info *iinfo;
> >  	char *name;
> >  	int err;
> > +	int fd = -1;
> > +
> > +	iinfo = HOSTFS_I(dentry->d_inode);
> > +	if (iinfo != NULL)
> > +		fd = iinfo->fd;
> 
> iinfo cannot be NULL, so please remove that if. HOSTFS_I does not access a 
> field of d_inode; rather, d_inode points to a field of iinfo, i.e. the 
> vfs_inode field of struct hostfs_inode_info.

That's good to know =) I'll fix it.


> I do not like the below code. The different code is for setting buf; what 
> follows that is common to all cases, and the conversion probably should be 
> factored out into a conversion function for better clarity: verifying what 
> the code does is difficult here.

I agree. I tried to make the changes to look as much as possible to the
original, but if you want me to reorganize that code a bit, I'll be glad
to give it a try.


I'll address all these issues and post and updated patch (probably
tomorrow).

Thanks a lot,
		Alberto



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Re: [uml-devel] [PATCH] Make hostfs_setattr() support operations on closed files.

[Alberto Bertogli]

[-- Attachment #1: Type: text/plain, Size: 541 bytes --]

On Tue, Apr 24, 2007 at 11:26:26AM -0300, Alberto Bertogli wrote:
> This patch allows hostfs_setattr() to work on closed files by calling
> set_attr() (the userspace part) with the inode's fd.
>
[...]
> 
>  fs/hostfs/hostfs.h      |    4 +-
>  fs/hostfs/hostfs_kern.c |   10 ++++-
>  fs/hostfs/hostfs_user.c |   89 ++++++++++++++++++++++++++++++++++++++++-------
>  3 files changed, 86 insertions(+), 17 deletions(-)

Here (as an inline attachment) is the updated patch that (hopefully)
address Blaisorblade's comments.

Thanks,
		Alberto



[-- Attachment #2: 0001-Make-hostfs_setattr-support-operations-on-unlinked.patch --]
[-- Type: text/plain, Size: 7690 bytes --]

From af922e915c05e32f0392b234e047f9aa9857fb80 Mon Sep 17 00:00:00 2001
From: Alberto Bertogli <albertito@gmail.com>
Date: Thu, 26 Apr 2007 01:57:07 -0300
Subject: [PATCH] Make hostfs_setattr() support operations on unlinked open files.

This patch allows hostfs_setattr() to work on unlinked open files by
calling set_attr() (the userspace part) with the inode's fd.

Without this, applications that depend on doing attribute changes to
unlinked open files will fail.

It works by using the fd versions instead of the path ones (for example
fchmod() instead of chmod(), fchown() instead of chown()) when an fd is
available.

Signed-off-by: Alberto Bertogli <albertito@gmail.com>
---
 fs/hostfs/hostfs.h      |    4 +-
 fs/hostfs/hostfs_kern.c |    6 ++-
 fs/hostfs/hostfs_user.c |  108 +++++++++++++++++++++++++++++-----------------
 3 files changed, 74 insertions(+), 44 deletions(-)

diff --git a/fs/hostfs/hostfs.h b/fs/hostfs/hostfs.h
index 70543b1..d8850c7 100644
--- a/fs/hostfs/hostfs.h
+++ b/fs/hostfs/hostfs.h
@@ -55,7 +55,7 @@ extern int stat_file(const char *path, unsigned long long *inode_out,
 		     int *mode_out, int *nlink_out, int *uid_out, int *gid_out,
 		     unsigned long long *size_out, struct timespec *atime_out,
 		     struct timespec *mtime_out, struct timespec *ctime_out,
-		     int *blksize_out, unsigned long long *blocks_out);
+		     int *blksize_out, unsigned long long *blocks_out, int fd);
 extern int access_file(char *path, int r, int w, int x);
 extern int open_file(char *path, int r, int w, int append);
 extern int file_type(const char *path, int *maj, int *min);
@@ -71,7 +71,7 @@ extern int lseek_file(int fd, long long offset, int whence);
 extern int fsync_file(int fd, int datasync);
 extern int file_create(char *name, int ur, int uw, int ux, int gr,
 		       int gw, int gx, int or, int ow, int ox);
-extern int set_attr(const char *file, struct hostfs_iattr *attrs);
+extern int set_attr(const char *file, struct hostfs_iattr *attrs, int fd);
 extern int make_symlink(const char *from, const char *to);
 extern int unlink_file(const char *file);
 extern int do_mkdir(const char *file, int mode);
diff --git a/fs/hostfs/hostfs_kern.c b/fs/hostfs/hostfs_kern.c
index fd301a9..4e8bb2f 100644
--- a/fs/hostfs/hostfs_kern.c
+++ b/fs/hostfs/hostfs_kern.c
@@ -147,7 +147,7 @@ static int read_name(struct inode *ino, char *name)
 
 	err = stat_file(name, &i_ino, &i_mode, &i_nlink, &ino->i_uid,
 			&ino->i_gid, &i_size, &ino->i_atime, &ino->i_mtime,
-			&ino->i_ctime, &i_blksize, &i_blocks);
+			&ino->i_ctime, &i_blksize, &i_blocks, -1);
 	if(err)
 		return(err);
 
@@ -820,6 +820,8 @@ int hostfs_setattr(struct dentry *dentry, struct iattr *attr)
 	char *name;
 	int err;
 
+	int fd = HOSTFS_I(dentry->d_inode)->fd;
+
 	err = inode_change_ok(dentry->d_inode, attr);
 	if (err)
 		return err;
@@ -864,7 +866,7 @@ int hostfs_setattr(struct dentry *dentry, struct iattr *attr)
 	}
 	name = dentry_name(dentry, 0);
 	if(name == NULL) return(-ENOMEM);
-	err = set_attr(name, &attrs);
+	err = set_attr(name, &attrs, fd);
 	kfree(name);
 	if(err)
 		return(err);
diff --git a/fs/hostfs/hostfs_user.c b/fs/hostfs/hostfs_user.c
index 1ed5ea3..0acf562 100644
--- a/fs/hostfs/hostfs_user.c
+++ b/fs/hostfs/hostfs_user.c
@@ -21,12 +21,16 @@ int stat_file(const char *path, unsigned long long *inode_out, int *mode_out,
 	      int *nlink_out, int *uid_out, int *gid_out,
 	      unsigned long long *size_out, struct timespec *atime_out,
 	      struct timespec *mtime_out, struct timespec *ctime_out,
-	      int *blksize_out, unsigned long long *blocks_out)
+	      int *blksize_out, unsigned long long *blocks_out, int fd)
 {
 	struct stat64 buf;
 
-	if(lstat64(path, &buf) < 0)
+	if(fd >= 0) {
+		if (fstat64(fd, &buf) < 0)
+			return(-errno);
+	} else if(lstat64(path, &buf) < 0) {
 		return(-errno);
+	}
 
 	if(inode_out != NULL) *inode_out = buf.st_ino;
 	if(mode_out != NULL) *mode_out = buf.st_mode;
@@ -202,58 +206,82 @@ int file_create(char *name, int ur, int uw, int ux, int gr,
 	return(fd);
 }
 
-int set_attr(const char *file, struct hostfs_iattr *attrs)
+int set_attr(const char *file, struct hostfs_iattr *attrs, int fd)
 {
-	struct utimbuf buf;
+	struct timeval times[2];
+	struct timespec atime_ts, mtime_ts;
 	int err, ma;
 
-	if(attrs->ia_valid & HOSTFS_ATTR_MODE){
-		if(chmod(file, attrs->ia_mode) != 0) return(-errno);
-	}
-	if(attrs->ia_valid & HOSTFS_ATTR_UID){
-		if(chown(file, attrs->ia_uid, -1)) return(-errno);
+	if (attrs->ia_valid & HOSTFS_ATTR_MODE) {
+		if (fd >= 0) {
+			if (fchmod(fd, attrs->ia_mode) != 0)
+				return (-errno);
+		} else if (chmod(file, attrs->ia_mode) != 0) {
+			return (-errno);
+		}
 	}
-	if(attrs->ia_valid & HOSTFS_ATTR_GID){
-		if(chown(file, -1, attrs->ia_gid)) return(-errno);
+	if (attrs->ia_valid & HOSTFS_ATTR_UID) {
+		if (fd >= 0) {
+			if (fchown(fd, attrs->ia_uid, -1))
+				return (-errno);
+		} else if(chown(file, attrs->ia_uid, -1)) {
+			return (-errno);
+		}
 	}
-	if(attrs->ia_valid & HOSTFS_ATTR_SIZE){
-		if(truncate(file, attrs->ia_size)) return(-errno);
+	if (attrs->ia_valid & HOSTFS_ATTR_GID) {
+		if (fd >= 0) {
+			if (fchown(fd, -1, attrs->ia_gid))
+				return (-errno);
+		} else if (chown(file, -1, attrs->ia_gid)) {
+			return (-errno);
+		}
 	}
-	ma = HOSTFS_ATTR_ATIME_SET | HOSTFS_ATTR_MTIME_SET;
-	if((attrs->ia_valid & ma) == ma){
-		buf.actime = attrs->ia_atime.tv_sec;
-		buf.modtime = attrs->ia_mtime.tv_sec;
-		if(utime(file, &buf) != 0) return(-errno);
+	if (attrs->ia_valid & HOSTFS_ATTR_SIZE) {
+		if (fd >= 0) {
+			if (ftruncate(fd, attrs->ia_size))
+				return (-errno);
+		} else if (truncate(file, attrs->ia_size)) {
+			return (-errno);
+		}
 	}
-	else {
-		struct timespec ts;
-
-		if(attrs->ia_valid & HOSTFS_ATTR_ATIME_SET){
-			err = stat_file(file, NULL, NULL, NULL, NULL, NULL,
-					NULL, NULL, &ts, NULL, NULL, NULL);
-			if(err != 0)
-				return(err);
-			buf.actime = attrs->ia_atime.tv_sec;
-			buf.modtime = ts.tv_sec;
-			if(utime(file, &buf) != 0)
-				return(-errno);
+
+	/* Update accessed and/or modified time, in two parts: first set
+	 * times according to the changes to perform, and then call futimes()
+	 * or utimes() to apply them. */
+	ma = (HOSTFS_ATTR_ATIME_SET | HOSTFS_ATTR_MTIME_SET);
+	if (attrs->ia_valid & ma) {
+		err = stat_file(file, NULL, NULL, NULL, NULL, NULL, NULL,
+				&atime_ts, &mtime_ts, NULL, NULL, NULL, fd);
+		if (err != 0)
+			return err;
+
+		times[0].tv_sec = atime_ts.tv_sec;
+		times[0].tv_usec = atime_ts.tv_nsec * 1000;
+		times[1].tv_sec = mtime_ts.tv_sec;
+		times[1].tv_usec = mtime_ts.tv_nsec * 1000;
+
+		if (attrs->ia_valid & HOSTFS_ATTR_ATIME_SET) {
+			times[0].tv_sec = attrs->ia_atime.tv_sec;
+			times[0].tv_usec = attrs->ia_atime.tv_nsec * 1000;
 		}
-		if(attrs->ia_valid & HOSTFS_ATTR_MTIME_SET){
-			err = stat_file(file, NULL, NULL, NULL, NULL, NULL,
-					NULL, &ts, NULL, NULL, NULL, NULL);
-			if(err != 0)
-				return(err);
-			buf.actime = ts.tv_sec;
-			buf.modtime = attrs->ia_mtime.tv_sec;
-			if(utime(file, &buf) != 0)
-				return(-errno);
+		if (attrs->ia_valid & HOSTFS_ATTR_MTIME_SET) {
+			times[1].tv_sec = attrs->ia_mtime.tv_sec;
+			times[1].tv_usec = attrs->ia_mtime.tv_nsec * 1000;
+		}
+
+		if (fd >= 0) {
+			if (futimes(fd, times) != 0)
+				return (-errno);
+		} else if (utimes(file, times) != 0) {
+			return (-errno);
 		}
 	}
+
 	if(attrs->ia_valid & HOSTFS_ATTR_CTIME) ;
 	if(attrs->ia_valid & (HOSTFS_ATTR_ATIME | HOSTFS_ATTR_MTIME)){
 		err = stat_file(file, NULL, NULL, NULL, NULL, NULL, NULL,
 				&attrs->ia_atime, &attrs->ia_mtime, NULL,
-				NULL, NULL);
+				NULL, NULL, fd);
 		if(err != 0) return(err);
 	}
 	return(0);
-- 
1.5.1.1


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