Commit d3fec424 authored by Jan Harkes's avatar Jan Harkes Committed by Linus Torvalds
Browse files

coda: remove CODA_STORE/CODA_RELEASE upcalls 



This is an variation on the patch sent by Christoph Hellwig which kills
file_count abuse by the Coda kernel module by moving the coda_flush
functionality into coda_release.  However part of reason we were using the
coda_flush callback was to allow Coda to pass errors that occur during
writeback from the userspace cache manager back to close().

As Al Viro explained on linux-fsdevel, it is impossible to guarantee that
such errors can in fact be returned back to the caller.  There are many
cases where the last reference to a file is not released by the close
system call and it is also impossible to pick some close as a 'last-close'
and delay it until all other references have been destroyed.

The CODA_STORE/CODA_RELEASE upcall combination is clearly a broken design,
and it is better to remove it completely.

Signed-off-by: default avatarJan Harkes <jaharkes@cs.cmu.edu>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Al Viro <viro@ftp.linux.org.uk>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent b5073173

fs/coda/dir.c

+0 −1
Original line number Diff line number Diff line
@@ -86,7 +86,6 @@ const struct file_operations coda_dir_operations = { 
	.read		= generic_read_dir,

	.readdir	= coda_readdir,

	.open		= coda_open,

	.flush		= coda_flush,

	.release	= coda_release,

	.fsync		= coda_fsync,

};

fs/coda/file.c

+6 −59
Original line number Diff line number Diff line
@@ -25,10 +25,6 @@ 


#include "coda_int.h"



/* if CODA_STORE fails with EOPNOTSUPP, venus clearly doesn't support

 * CODA_STORE/CODA_RELEASE and we fall back on using the CODA_CLOSE upcall */

static int use_coda_close;



static ssize_t

coda_file_read(struct file *coda_file, char __user *buf, size_t count, loff_t *ppos)

{
@@ -163,47 +159,6 @@ int coda_open(struct inode *coda_inode, struct file *coda_file) 
	return 0;

}



int coda_flush(struct file *coda_file, fl_owner_t id)

{

	unsigned short flags = coda_file->f_flags & ~O_EXCL;

	unsigned short coda_flags = coda_flags_to_cflags(flags);

	struct coda_file_info *cfi;

	struct inode *coda_inode;

	int err = 0, fcnt;



	lock_kernel();



	/* last close semantics */

	fcnt = file_count(coda_file);

	if (fcnt > 1)

		goto out;



	/* No need to make an upcall when we have not made any modifications

	 * to the file */

	if ((coda_file->f_flags & O_ACCMODE) == O_RDONLY)

		goto out;



	if (use_coda_close)

		goto out;



	cfi = CODA_FTOC(coda_file);

	BUG_ON(!cfi || cfi->cfi_magic != CODA_MAGIC);



	coda_inode = coda_file->f_path.dentry->d_inode;



	err = venus_store(coda_inode->i_sb, coda_i2f(coda_inode), coda_flags,

			  coda_file->f_uid);



	if (err == -EOPNOTSUPP) {

		use_coda_close = 1;

		err = 0;

	}



out:

	unlock_kernel();

	return err;

}



int coda_release(struct inode *coda_inode, struct file *coda_file)

{

	unsigned short flags = (coda_file->f_flags) & (~O_EXCL);
@@ -215,19 +170,9 @@ int coda_release(struct inode *coda_inode, struct file *coda_file) 


	lock_kernel();



	if (!use_coda_close) {

		err = venus_release(coda_inode->i_sb, coda_i2f(coda_inode),

				    coda_flags);

		if (err == -EOPNOTSUPP) {

			use_coda_close = 1;

			err = 0;

		}

	}



	cfi = CODA_FTOC(coda_file);

	BUG_ON(!cfi || cfi->cfi_magic != CODA_MAGIC);



	if (use_coda_close)

	err = venus_close(coda_inode->i_sb, coda_i2f(coda_inode),

			  coda_flags, coda_file->f_uid);
@@ -246,7 +191,10 @@ int coda_release(struct inode *coda_inode, struct file *coda_file) 
	coda_file->private_data = NULL;



	unlock_kernel();

	return err;



	/* VFS fput ignores the return value from file_operations->release, so

	 * there is no use returning an error here */

	return 0;

}



int coda_fsync(struct file *coda_file, struct dentry *coda_dentry, int datasync)
@@ -288,7 +236,6 @@ const struct file_operations coda_file_operations = { 
	.write		= coda_file_write,

	.mmap		= coda_file_mmap,

	.open		= coda_open,

	.flush		= coda_flush,

	.release	= coda_release,

	.fsync		= coda_fsync,

	.splice_read	= coda_file_splice_read,

fs/coda/upcall.c

+1 −48
Original line number Diff line number Diff line
@@ -160,53 +160,6 @@ int venus_lookup(struct super_block *sb, struct CodaFid *fid, 
	return error;

}



int venus_store(struct super_block *sb, struct CodaFid *fid, int flags,

                vuid_t uid)

{

        union inputArgs *inp;

        union outputArgs *outp;

        int insize, outsize, error;

#ifdef CONFIG_CODA_FS_OLD_API

	struct coda_cred cred = { 0, };

	cred.cr_fsuid = uid;

#endif

	

	insize = SIZE(store);

	UPARG(CODA_STORE);

	

#ifdef CONFIG_CODA_FS_OLD_API

	memcpy(&(inp->ih.cred), &cred, sizeof(cred));

#else

	inp->ih.uid = uid;

#endif

	

        inp->coda_store.VFid = *fid;

        inp->coda_store.flags = flags;



	error = coda_upcall(coda_vcp(sb), insize, &outsize, inp);



	CODA_FREE(inp, insize);

        return error;

}



int venus_release(struct super_block *sb, struct CodaFid *fid, int flags)

{

        union inputArgs *inp;

        union outputArgs *outp;

        int insize, outsize, error;

	

	insize = SIZE(release);

	UPARG(CODA_RELEASE);

	

	inp->coda_release.VFid = *fid;

	inp->coda_release.flags = flags;



	error = coda_upcall(coda_vcp(sb), insize, &outsize, inp);



	CODA_FREE(inp, insize);

	return error;

}



int venus_close(struct super_block *sb, struct CodaFid *fid, int flags,

		vuid_t uid)

{

include/linux/coda_linux.h

+0 −1
Original line number Diff line number Diff line
@@ -36,7 +36,6 @@ extern const struct file_operations coda_ioctl_operations; 


/* operations shared over more than one file */

int coda_open(struct inode *i, struct file *f);

int coda_flush(struct file *f, fl_owner_t id);

int coda_release(struct inode *i, struct file *f);

int coda_permission(struct inode *inode, int mask, struct nameidata *nd);

int coda_revalidate_inode(struct dentry *);

include/linux/coda_psdev.h

+0 −3
Original line number Diff line number Diff line
@@ -33,9 +33,6 @@ int venus_setattr(struct super_block *, struct CodaFid *, struct coda_vattr *); 
int venus_lookup(struct super_block *sb, struct CodaFid *fid, 

		 const char *name, int length, int *type, 

		 struct CodaFid *resfid);

int venus_store(struct super_block *sb, struct CodaFid *fid, int flags,

		vuid_t uid);

int venus_release(struct super_block *sb, struct CodaFid *fid, int flags);

int venus_close(struct super_block *sb, struct CodaFid *fid, int flags,

		vuid_t uid);

int venus_open(struct super_block *sb, struct CodaFid *fid, int flags,

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