From f91b90993f0d286be89f06c2f547ced8cfe291c6 Mon Sep 17 00:00:00 2001 From: Martin Stava Date: Mon, 2 Nov 2009 08:39:35 -0600 Subject: [PATCH 1/3] 9p: fix a small bug in readdir for long directories Here is a proposed patch for bug in readdir. Listing of dirs with many files fails without this patch. Signed-off-by: Martin Stava Signed-off-by: Eric Van Hensbergen --- fs/9p/vfs_dir.c | 1 + 1 file changed, 1 insertion(+) diff --git a/fs/9p/vfs_dir.c b/fs/9p/vfs_dir.c index 873cd31baa47..cae53d405f21 100644 --- a/fs/9p/vfs_dir.c +++ b/fs/9p/vfs_dir.c @@ -90,6 +90,7 @@ static int v9fs_dir_readdir(struct file *filp, void *dirent, filldir_t filldir) if (err <= 0) break; + i = 0; n = err; while (i < n) { err = p9stat_read(statbuf + i, buflen-i, &st, From 2511cd0b3b9e9b1c3e9360cc565c3745ac3f3f3f Mon Sep 17 00:00:00 2001 From: Martin Stava Date: Mon, 2 Nov 2009 08:39:34 -0600 Subject: [PATCH 2/3] 9p: fix readlink I do not know if you've looked on the patch, but unfortunately it is incorrect. A suggested better version is in this email (the old version didn't work in case the user provided buffer was not long enough - it incorrectly appended null byte on a position of last char, and thus broke the contract of the readlink method). However, I'm still not sure this is 100% correct thing to do, I think readlink is supposed to return buffer without last null byte in all cases, but we do return last null byte (even the old version).. on the other hand it is likely unspecified what is in the remaining part of the buffer, so null character may be fine there ;): Signed-off-by: Martin Stava Signed-off-by: Eric Van Hensbergen --- fs/9p/vfs_inode.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) diff --git a/fs/9p/vfs_inode.c b/fs/9p/vfs_inode.c index 5947628aefef..18f74ec4dce9 100644 --- a/fs/9p/vfs_inode.c +++ b/fs/9p/vfs_inode.c @@ -994,8 +994,7 @@ static int v9fs_readlink(struct dentry *dentry, char *buffer, int buflen) P9_DPRINTK(P9_DEBUG_VFS, "%s -> %s (%s)\n", dentry->d_name.name, st->extension, buffer); - retval = buflen; - + retval = strnlen(buffer, buflen); done: kfree(st); return retval; @@ -1062,7 +1061,7 @@ static void *v9fs_vfs_follow_link(struct dentry *dentry, struct nameidata *nd) __putname(link); link = ERR_PTR(len); } else - link[len] = 0; + link[min(len, PATH_MAX-1)] = 0; } nd_set_link(nd, link); From 3e2796a90cf349527e50b3bc4d0b2f4019b1ce7a Mon Sep 17 00:00:00 2001 From: Eric Van Hensbergen Date: Mon, 2 Nov 2009 08:39:28 -0600 Subject: [PATCH 3/3] 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); }