Commit 3e2796a9 authored by Eric Van Hensbergen's avatar Eric Van Hensbergen
Browse files

9p: fix readdir corner cases 



The patch below also addresses a couple of other corner cases in readdir
seen with a large (e.g. 64k) msize.  I'm not sure what people think of
my co-opting of fid->aux here.  I'd be happy to rework if there's a better
way.

When the size of the user supplied buffer passed to readdir is smaller
than the data returned in one go by the 9P read request, v9fs_dir_readdir()
currently discards extra data so that, on the next call, a 9P read
request will be issued with offset < previous offset + bytes returned,
which voilates the constraint described in paragraph 3 of read(5) description.
This patch preseves the leftover data in fid->aux for use in the next call.

Signed-off-by: default avatarJim Garlick <garlick@llnl.gov>
Signed-off-by: default avatarEric Van Hensbergen <ericvh@gmail.com>
parent 2511cd0b

fs/9p/vfs_dir.c

+67 −27
Original line number Original line Diff line number Diff line
@@ -39,6 +39,24 @@ 
#include "v9fs_vfs.h"

#include "v9fs_vfs.h"

#include "fid.h"

#include "fid.h"





/**

 * struct p9_rdir - readdir accounting

 * @mutex: mutex protecting readdir

 * @head: start offset of current dirread buffer

 * @tail: end offset of current dirread buffer

 * @buf: dirread buffer

 *

 * private structure for keeping track of readdir

 * allocated on demand

 */



struct p9_rdir {

	struct mutex mutex;

	int head;

	int tail;

	uint8_t *buf;

};



/**

/**

 * dt_type - return file type

 * dt_type - return file type

 * @mistat: mistat structure

 * @mistat: mistat structure
@@ -70,57 +88,79 @@ static int v9fs_dir_readdir(struct file *filp, void *dirent, filldir_t filldir) 
{

{

	int over;

	int over;

	struct p9_wstat st;

	struct p9_wstat st;

	int err;

	int err = 0;

	struct p9_fid *fid;

	struct p9_fid *fid;

	int buflen;

	int buflen;

	char *statbuf;

	int reclen = 0;

	int n, i = 0;

	struct p9_rdir *rdir;





	P9_DPRINTK(P9_DEBUG_VFS, "name %s\n", filp->f_path.dentry->d_name.name);

	P9_DPRINTK(P9_DEBUG_VFS, "name %s\n", filp->f_path.dentry->d_name.name);

	fid = filp->private_data;

	fid = filp->private_data;





	buflen = fid->clnt->msize - P9_IOHDRSZ;

	buflen = fid->clnt->msize - P9_IOHDRSZ;

	statbuf = kmalloc(buflen, GFP_KERNEL);

	if (!statbuf)

		return -ENOMEM;





	while (1) {

	/* allocate rdir on demand */

		err = v9fs_file_readn(filp, statbuf, NULL, buflen,

	if (!fid->rdir) {

								fid->rdir_fpos);

		rdir = kmalloc(sizeof(struct p9_rdir) + buflen, GFP_KERNEL);



		if (rdir == NULL) {

			err = -ENOMEM;

			goto exit;

		}

		spin_lock(&filp->f_dentry->d_lock);

		if (!fid->rdir) {

			rdir->buf = (uint8_t *)rdir + sizeof(struct p9_rdir);

			mutex_init(&rdir->mutex);

			rdir->head = rdir->tail = 0;

			fid->rdir = (void *) rdir;

			rdir = NULL;

		}

		spin_unlock(&filp->f_dentry->d_lock);

		kfree(rdir);

	}

	rdir = (struct p9_rdir *) fid->rdir;



	err = mutex_lock_interruptible(&rdir->mutex);

	while (err == 0) {

		if (rdir->tail == rdir->head) {

			err = v9fs_file_readn(filp, rdir->buf, NULL,

							buflen, filp->f_pos);

			if (err <= 0)

			if (err <= 0)

			break;

				goto unlock_and_exit;





		i = 0;

			rdir->head = 0;

		n = err;

			rdir->tail = err;

		while (i < n) {

		}

			err = p9stat_read(statbuf + i, buflen-i, &st,



		while (rdir->head < rdir->tail) {

			err = p9stat_read(rdir->buf + rdir->head,

						buflen - rdir->head, &st,

						fid->clnt->dotu);

						fid->clnt->dotu);

			if (err) {

			if (err) {

				P9_DPRINTK(P9_DEBUG_VFS, "returned %d\n", err);

				P9_DPRINTK(P9_DEBUG_VFS, "returned %d\n", err);

				err = -EIO;

				err = -EIO;

				p9stat_free(&st);

				p9stat_free(&st);

				goto free_and_exit;

				goto unlock_and_exit;

			}

			}



			reclen = st.size+2;

			i += st.size+2;

			fid->rdir_fpos += st.size+2;





			over = filldir(dirent, st.name, strlen(st.name),

			over = filldir(dirent, st.name, strlen(st.name),

			    filp->f_pos, v9fs_qid2ino(&st.qid), dt_type(&st));

			    filp->f_pos, v9fs_qid2ino(&st.qid), dt_type(&st));





			filp->f_pos += st.size+2;



			p9stat_free(&st);

			p9stat_free(&st);





			if (over) {

			if (over) {

				err = 0;

				err = 0;

				goto free_and_exit;

				goto unlock_and_exit;

			}

			}

			rdir->head += reclen;

			filp->f_pos += reclen;

		}

		}

	}

	}





free_and_exit:

unlock_and_exit:

	kfree(statbuf);

	mutex_unlock(&rdir->mutex);

exit:

	return err;

	return err;

}

}

include/net/9p/client.h

+3 −4
Original line number Original line Diff line number Diff line
@@ -159,8 +159,7 @@ struct p9_client { 
 * @qid: the &p9_qid server identifier this handle points to

 * @qid: the &p9_qid server identifier this handle points to

 * @iounit: the server reported maximum transaction size for this file

 * @iounit: the server reported maximum transaction size for this file

 * @uid: the numeric uid of the local user who owns this handle

 * @uid: the numeric uid of the local user who owns this handle

 * @aux: transport specific information (unused?)

 * @rdir: readdir accounting structure (allocated on demand)

 * @rdir_fpos: tracks offset of file position when reading directory contents

 * @flist: per-client-instance fid tracking

 * @flist: per-client-instance fid tracking

 * @dlist: per-dentry fid tracking

 * @dlist: per-dentry fid tracking

 *

 *
@@ -174,9 +173,9 @@ struct p9_fid { 
	struct p9_qid qid;

	struct p9_qid qid;

	u32 iounit;

	u32 iounit;

	uid_t uid;

	uid_t uid;

	void *aux;





	int rdir_fpos;

	void *rdir;



	struct list_head flist;

	struct list_head flist;

	struct list_head dlist;	/* list of all fids attached to a dentry */

	struct list_head dlist;	/* list of all fids attached to a dentry */

};

};

net/9p/client.c

+2 −3
Original line number Original line Diff line number Diff line
@@ -582,11 +582,9 @@ static struct p9_fid *p9_fid_create(struct p9_client *clnt) 




	memset(&fid->qid, 0, sizeof(struct p9_qid));

	memset(&fid->qid, 0, sizeof(struct p9_qid));

	fid->mode = -1;

	fid->mode = -1;

	fid->rdir_fpos = 0;

	fid->uid = current_fsuid();

	fid->uid = current_fsuid();

	fid->clnt = clnt;

	fid->clnt = clnt;

	fid->aux = NULL;

	fid->rdir = NULL;



	spin_lock_irqsave(&clnt->lock, flags);

	spin_lock_irqsave(&clnt->lock, flags);

	list_add(&fid->flist, &clnt->fidlist);

	list_add(&fid->flist, &clnt->fidlist);

	spin_unlock_irqrestore(&clnt->lock, flags);

	spin_unlock_irqrestore(&clnt->lock, flags);
@@ -609,6 +607,7 @@ static void p9_fid_destroy(struct p9_fid *fid) 
	spin_lock_irqsave(&clnt->lock, flags);

	spin_lock_irqsave(&clnt->lock, flags);

	list_del(&fid->flist);

	list_del(&fid->flist);

	spin_unlock_irqrestore(&clnt->lock, flags);

	spin_unlock_irqrestore(&clnt->lock, flags);

	kfree(fid->rdir);

	kfree(fid);

	kfree(fid);

}

}

CRA Git | Maintained and supported by SUSTech CRA and CCSE