From 3e2796a90cf349527e50b3bc4d0b2f4019b1ce7a Mon Sep 17 00:00:00 2001 From: Eric Van Hensbergen Date: Mon, 2 Nov 2009 08:39:28 -0600 Subject: [PATCH] 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 Signed-off-by: Eric Van Hensbergen --- fs/9p/vfs_dir.c | 90 +++++++++++++++++++++++++++++------------ include/net/9p/client.h | 7 ++-- net/9p/client.c | 5 +-- 3 files changed, 70 insertions(+), 32 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 @@ -39,6 +39,24 @@ #include "v9fs_vfs.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 * @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; + /* allocate rdir on demand */ + if (!fid->rdir) { + rdir = kmalloc(sizeof(struct p9_rdir) + buflen, GFP_KERNEL); - i = 0; - n = err; - while (i < n) { - err = p9stat_read(statbuf + i, buflen-i, &st, - fid->clnt->dotu); + 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); }