From 0b8dd17762194ec77066d339e0b2866b0c66b715 Mon Sep 17 00:00:00 2001 From: Latchesar Ionkov Date: Tue, 27 Sep 2005 21:45:24 -0700 Subject: [PATCH] v9fs: fix races in fid allocation Fid management cleanup. The patch attempts to fix the races in dentry's fid management. Dentries don't keep the opened fids anymore, they are moved to the file structs. Ideally there should be no more than one fid with fidcreate equal to zero in the dentry's list of fids. v9fs_fid_create initializes the important fields (fid, fidcreated) before v9fs_fid is added to the list. v9fs_fid_lookup returns only fids that are not created by v9fs_create. v9fs_fid_get_created returns the fid created by the same process by v9fs_create (if any) and removes it from dentry's list Signed-off-by: Latchesar Ionkov Cc: Eric Van Hensbergen Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/9p/vfs_file.c | 88 ++++++++++++++++++-------------------------------------- 1 file changed, 28 insertions(+), 60 deletions(-) (limited to 'fs/9p/vfs_file.c') diff --git a/fs/9p/vfs_file.c b/fs/9p/vfs_file.c index 1f8ae7d580ab..a4799e971d1c 100644 --- a/fs/9p/vfs_file.c +++ b/fs/9p/vfs_file.c @@ -53,30 +53,36 @@ int v9fs_file_open(struct inode *inode, struct file *file) { struct v9fs_session_info *v9ses = v9fs_inode2v9ses(inode); - struct v9fs_fid *v9fid = v9fs_fid_lookup(file->f_dentry, FID_WALK); - struct v9fs_fid *v9newfid = NULL; + struct v9fs_fid *v9fid, *fid; struct v9fs_fcall *fcall = NULL; int open_mode = 0; unsigned int iounit = 0; int newfid = -1; long result = -1; - dprintk(DEBUG_VFS, "inode: %p file: %p v9fid= %p\n", inode, file, - v9fid); + dprintk(DEBUG_VFS, "inode: %p file: %p \n", inode, file); + + v9fid = v9fs_fid_get_created(file->f_dentry); + if (!v9fid) + v9fid = v9fs_fid_lookup(file->f_dentry); if (!v9fid) { - struct dentry *dentry = file->f_dentry; dprintk(DEBUG_ERROR, "Couldn't resolve fid from dentry\n"); + return -EBADF; + } - /* XXX - some duplication from lookup, generalize later */ - /* basically vfs_lookup is too heavy weight */ - v9fid = v9fs_fid_lookup(file->f_dentry, FID_OP); - if (!v9fid) - return -EBADF; + if (!v9fid->fidcreate) { + fid = kmalloc(sizeof(struct v9fs_fid), GFP_KERNEL); + if (fid == NULL) { + dprintk(DEBUG_ERROR, "Out of Memory\n"); + return -ENOMEM; + } - v9fid = v9fs_fid_lookup(dentry->d_parent, FID_WALK); - if (!v9fid) - return -EBADF; + fid->fidopen = 0; + fid->fidcreate = 0; + fid->fidclunked = 0; + fid->iounit = 0; + fid->v9ses = v9ses; newfid = v9fs_get_idpool(&v9ses->fidpool); if (newfid < 0) { @@ -85,58 +91,16 @@ int v9fs_file_open(struct inode *inode, struct file *file) } result = - v9fs_t_walk(v9ses, v9fid->fid, newfid, - (char *)file->f_dentry->d_name.name, NULL); + v9fs_t_walk(v9ses, v9fid->fid, newfid, NULL, NULL); + if (result < 0) { v9fs_put_idpool(newfid, &v9ses->fidpool); dprintk(DEBUG_ERROR, "rewalk didn't work\n"); return -EBADF; } - v9fid = v9fs_fid_create(dentry); - if (v9fid == NULL) { - dprintk(DEBUG_ERROR, "couldn't insert\n"); - return -ENOMEM; - } - v9fid->fid = newfid; - } - - if (v9fid->fidcreate) { - /* create case */ - newfid = v9fid->fid; - iounit = v9fid->iounit; - v9fid->fidcreate = 0; - } else { - if (!S_ISDIR(inode->i_mode)) - newfid = v9fid->fid; - else { - newfid = v9fs_get_idpool(&v9ses->fidpool); - if (newfid < 0) { - eprintk(KERN_WARNING, "allocation failed\n"); - return -ENOSPC; - } - /* This would be a somewhat critical clone */ - result = - v9fs_t_walk(v9ses, v9fid->fid, newfid, NULL, - &fcall); - if (result < 0) { - dprintk(DEBUG_ERROR, "clone error: %s\n", - FCALL_ERROR(fcall)); - kfree(fcall); - return result; - } - - v9newfid = v9fs_fid_create(file->f_dentry); - v9newfid->fid = newfid; - v9newfid->qid = v9fid->qid; - v9newfid->iounit = v9fid->iounit; - v9newfid->fidopen = 0; - v9newfid->fidclunked = 0; - v9newfid->v9ses = v9ses; - v9fid = v9newfid; - kfree(fcall); - } - + fid->fid = newfid; + v9fid = fid; /* TODO: do special things for O_EXCL, O_NOFOLLOW, O_SYNC */ /* translate open mode appropriately */ open_mode = file->f_flags & 0x3; @@ -163,9 +127,13 @@ int v9fs_file_open(struct inode *inode, struct file *file) iounit = fcall->params.ropen.iounit; kfree(fcall); + } else { + /* create case */ + newfid = v9fid->fid; + iounit = v9fid->iounit; + v9fid->fidcreate = 0; } - file->private_data = v9fid; v9fid->rdir_pos = 0; -- cgit v1.2.3