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author | Eric Van Hensbergen <ericvh@gmail.com> | 2009-11-02 08:39:28 -0600 |
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committer | Eric Van Hensbergen <ericvh@gmail.com> | 2009-11-02 08:43:45 -0600 |
commit | 3e2796a90cf349527e50b3bc4d0b2f4019b1ce7a (patch) | |
tree | 80bddc0f5d36a589db5a77b9b60e4c94c75994ed /fs/9p/vfs_dir.c | |
parent | 2511cd0b3b9e9b1c3e9360cc565c3745ac3f3f3f (diff) | |
download | blackbird-op-linux-3e2796a90cf349527e50b3bc4d0b2f4019b1ce7a.tar.gz blackbird-op-linux-3e2796a90cf349527e50b3bc4d0b2f4019b1ce7a.zip |
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>
Diffstat (limited to 'fs/9p/vfs_dir.c')
-rw-r--r-- | fs/9p/vfs_dir.c | 94 |
1 files changed, 67 insertions, 27 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; } |