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

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
...@@ -39,6 +39,24 @@ ...@@ -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) ...@@ -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) /* allocate rdir on demand */
return -ENOMEM; if (!fid->rdir) {
rdir = kmalloc(sizeof(struct p9_rdir) + buflen, GFP_KERNEL);
while (1) {
err = v9fs_file_readn(filp, statbuf, NULL, buflen, if (rdir == NULL) {
fid->rdir_fpos); err = -ENOMEM;
if (err <= 0) goto exit;
break; }
spin_lock(&filp->f_dentry->d_lock);
i = 0; if (!fid->rdir) {
n = err; rdir->buf = (uint8_t *)rdir + sizeof(struct p9_rdir);
while (i < n) { mutex_init(&rdir->mutex);
err = p9stat_read(statbuf + i, buflen-i, &st, rdir->head = rdir->tail = 0;
fid->clnt->dotu); 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)
goto unlock_and_exit;
rdir->head = 0;
rdir->tail = err;
}
while (rdir->head < rdir->tail) {
err = p9stat_read(rdir->buf + rdir->head,
buflen - rdir->head, &st,
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;
} }
......
...@@ -159,8 +159,7 @@ struct p9_client { ...@@ -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 { ...@@ -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 */
}; };
......
...@@ -582,11 +582,9 @@ static struct p9_fid *p9_fid_create(struct p9_client *clnt) ...@@ -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) ...@@ -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);
} }
......
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