From b799bc7da0ce5ba4a988c521a8fb10452eb419f0 Mon Sep 17 00:00:00 2001 From: Boaz Harrosh Date: Sun, 25 Jan 2009 16:58:03 +0200 Subject: [SCSI] osd_uld: API for retrieving osd devices from Kernel Kernel clients like exofs can retrieve struct osd_dev(s) by means of below API. + osduld_path_lookup() - given a path (e.g "/dev/osd0") locks and returns the corresponding struct osd_dev, which is then needed for subsequent libosd use. + osduld_put_device() - free up use of an osd_dev. Devices can be shared by multiple clients. The osd_uld_device's life time is governed by an embedded kref structure. The osd_uld_device holds an extra reference to both it's char-device and it's scsi_device, and will release these just before the final deallocation. There are three possible lock sources of the osd_uld_device 1. First and for most is the probe() function called by scsi-ml upon a successful login into a target. Released in release() when logout. 2. Second by user-mode file handles opened on the char-dev. 3. Third is here by Kernel users. All three locks must be removed before the osd_uld_device is freed. The MODULE has three lock sources as well: 1. scsi-ml at probe() time, removed after release(). (login/logout) 2. The user-mode file handles open/close. 3. Import symbols by client modules like exofs. TODO: This API is not enough for the pNFS-objects LD. A more versatile API will be needed. Proposed API could be: struct osd_dev *osduld_sysid_lookup(const char id[OSD_SYSTEMID_LEN]); Signed-off-by: Boaz Harrosh Signed-off-by: James Bottomley --- drivers/scsi/osd/osd_uld.c | 63 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 63 insertions(+) (limited to 'drivers/scsi/osd') diff --git a/drivers/scsi/osd/osd_uld.c b/drivers/scsi/osd/osd_uld.c index f6f9a99adaa..cd4ca7cd9f7 100644 --- a/drivers/scsi/osd/osd_uld.c +++ b/drivers/scsi/osd/osd_uld.c @@ -173,6 +173,69 @@ static const struct file_operations osd_fops = { .unlocked_ioctl = osd_uld_ioctl, }; +struct osd_dev *osduld_path_lookup(const char *path) +{ + struct nameidata nd; + struct inode *inode; + struct cdev *cdev; + struct osd_uld_device *uninitialized_var(oud); + int error; + + if (!path || !*path) { + OSD_ERR("Mount with !path || !*path\n"); + return ERR_PTR(-EINVAL); + } + + error = path_lookup(path, LOOKUP_FOLLOW, &nd); + if (error) { + OSD_ERR("path_lookup of %s faild=>%d\n", path, error); + return ERR_PTR(error); + } + + inode = nd.path.dentry->d_inode; + error = -EINVAL; /* Not the right device e.g osd_uld_device */ + if (!S_ISCHR(inode->i_mode)) { + OSD_DEBUG("!S_ISCHR()\n"); + goto out; + } + + cdev = inode->i_cdev; + if (!cdev) { + OSD_ERR("Before mounting an OSD Based filesystem\n"); + OSD_ERR(" user-mode must open+close the %s device\n", path); + OSD_ERR(" Example: bash: echo < %s\n", path); + goto out; + } + + /* The Magic wand. Is it our char-dev */ + /* TODO: Support sg devices */ + if (cdev->owner != THIS_MODULE) { + OSD_ERR("Error mounting %s - is not an OSD device\n", path); + goto out; + } + + oud = container_of(cdev, struct osd_uld_device, cdev); + + __uld_get(oud); + error = 0; + +out: + path_put(&nd.path); + return error ? ERR_PTR(error) : &oud->od; +} +EXPORT_SYMBOL(osduld_path_lookup); + +void osduld_put_device(struct osd_dev *od) +{ + if (od) { + struct osd_uld_device *oud = container_of(od, + struct osd_uld_device, od); + + __uld_put(oud); + } +} +EXPORT_SYMBOL(osduld_put_device); + /* * Scsi Device operations */ -- cgit v1.2.3