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authorEric Van Hensbergen <ericvh@gmail.com>2009-11-02 08:39:28 -0600
committerEric Van Hensbergen <ericvh@gmail.com>2009-11-02 08:43:45 -0600
commit3e2796a90cf349527e50b3bc4d0b2f4019b1ce7a (patch)
tree80bddc0f5d36a589db5a77b9b60e4c94c75994ed
parent2511cd0b3b9e9b1c3e9360cc565c3745ac3f3f3f (diff)
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: Jim Garlick <garlick@llnl.gov> Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>
-rw-r--r--fs/9p/vfs_dir.c94
-rw-r--r--include/net/9p/client.h7
-rw-r--r--net/9p/client.c5
3 files changed, 72 insertions, 34 deletions
diff --git a/fs/9p/vfs_dir.c b/fs/9p/vfs_dir.c
index cae53d405f21..15cce53bf61e 100644
--- a/fs/9p/vfs_dir.c
+++ b/fs/9p/vfs_dir.c
@@ -40,6 +40,24 @@
#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
* @mistat: mistat structure
*
@@ -70,57 +88,79 @@ static int v9fs_dir_readdir(struct file *filp, void *dirent, filldir_t filldir)
{
int over;
struct p9_wstat st;
- int err;
+ int err = 0;
struct p9_fid *fid;
int buflen;
- char *statbuf;
- int n, i = 0;
+ int reclen = 0;
+ struct p9_rdir *rdir;
P9_DPRINTK(P9_DEBUG_VFS, "name %s\n", filp->f_path.dentry->d_name.name);
fid = filp->private_data;
buflen = fid->clnt->msize - P9_IOHDRSZ;
- statbuf = kmalloc(buflen, GFP_KERNEL);
- if (!statbuf)
- return -ENOMEM;
-
- while (1) {
- err = v9fs_file_readn(filp, statbuf, NULL, buflen,
- fid->rdir_fpos);
- if (err <= 0)
- break;
-
- i = 0;
- n = err;
- while (i < n) {
- err = p9stat_read(statbuf + i, buflen-i, &st,
- fid->clnt->dotu);
+
+ /* allocate rdir on demand */
+ if (!fid->rdir) {
+ 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)
+ 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) {
P9_DPRINTK(P9_DEBUG_VFS, "returned %d\n", err);
err = -EIO;
p9stat_free(&st);
- goto free_and_exit;
+ goto unlock_and_exit;
}
-
- i += st.size+2;
- fid->rdir_fpos += st.size+2;
+ reclen = st.size+2;
over = filldir(dirent, st.name, strlen(st.name),
filp->f_pos, v9fs_qid2ino(&st.qid), dt_type(&st));
- filp->f_pos += st.size+2;
-
p9stat_free(&st);
if (over) {
err = 0;
- goto free_and_exit;
+ goto unlock_and_exit;
}
+ rdir->head += reclen;
+ filp->f_pos += reclen;
}
}
-free_and_exit:
- kfree(statbuf);
+unlock_and_exit:
+ mutex_unlock(&rdir->mutex);
+exit:
return err;
}
diff --git a/include/net/9p/client.h b/include/net/9p/client.h
index e26812274b75..fb00b329f0d3 100644
--- a/include/net/9p/client.h
+++ b/include/net/9p/client.h
@@ -159,8 +159,7 @@ struct p9_client {
* @qid: the &p9_qid server identifier this handle points to
* @iounit: the server reported maximum transaction size for this file
* @uid: the numeric uid of the local user who owns this handle
- * @aux: transport specific information (unused?)
- * @rdir_fpos: tracks offset of file position when reading directory contents
+ * @rdir: readdir accounting structure (allocated on demand)
* @flist: per-client-instance fid tracking
* @dlist: per-dentry fid tracking
*
@@ -174,9 +173,9 @@ struct p9_fid {
struct p9_qid qid;
u32 iounit;
uid_t uid;
- void *aux;
- int rdir_fpos;
+ void *rdir;
+
struct list_head flist;
struct list_head dlist; /* list of all fids attached to a dentry */
};
diff --git a/net/9p/client.c b/net/9p/client.c
index 5bf5f227dbe0..8af95b2dddd6 100644
--- a/net/9p/client.c
+++ b/net/9p/client.c
@@ -582,11 +582,9 @@ static struct p9_fid *p9_fid_create(struct p9_client *clnt)
memset(&fid->qid, 0, sizeof(struct p9_qid));
fid->mode = -1;
- fid->rdir_fpos = 0;
fid->uid = current_fsuid();
fid->clnt = clnt;
- fid->aux = NULL;
-
+ fid->rdir = NULL;
spin_lock_irqsave(&clnt->lock, flags);
list_add(&fid->flist, &clnt->fidlist);
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);
list_del(&fid->flist);
spin_unlock_irqrestore(&clnt->lock, flags);
+ kfree(fid->rdir);
kfree(fid);
}