resubmit: cciss: procfs updates to display info about many

volumes

This patch allows us to display information about all of the logical volumes
configured on a particular controller without stepping on memory even when
there are many volumes (128 or more) configured.
Please consider this for inclusion.

Signed-off-by: Mike Miller <mike.miller@hp.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

1 files changed, 157 insertions, 96 deletions

diff --git a/drivers/block/cciss.c b/drivers/block/cciss.c
index 9715be3f2487..f1e7390683fd 100644
--- a/drivers/block/cciss.c
+++ b/drivers/block/cciss.c
@@ -33,6 +33,7 @@
 #include <linux/blkpg.h>
 #include <linux/timer.h>
 #include <linux/proc_fs.h>
+#include <linux/seq_file.h>
 #include <linux/init.h>
 #include <linux/hdreg.h>
 #include <linux/spinlock.h>
@@ -174,8 +175,6 @@ static int sendcmd_withirq(__u8 cmd, int ctlr, void *buff, size_t size,
 static void fail_all_cmds(unsigned long ctlr);
 
 #ifdef CONFIG_PROC_FS
-static int cciss_proc_get_info(char *buffer, char **start, off_t offset,
-                               int length, int *eof, void *data);
 static void cciss_procinit(int i);
 #else
 static void cciss_procinit(int i)
@@ -240,24 +239,46 @@ static inline CommandList_struct *removeQ(CommandList_struct **Qptr,
  */
 #define ENG_GIG 1000000000
 #define ENG_GIG_FACTOR (ENG_GIG/512)
+#define ENGAGE_SCSI     "engage scsi"
 static const char *raid_label[] = { "0", "4", "1(1+0)", "5", "5+1", "ADG",
         "UNKNOWN"
 };
 
 static struct proc_dir_entry *proc_cciss;
 
-static int cciss_proc_get_info(char *buffer, char **start, off_t offset,
-                               int length, int *eof, void *data)
+static void cciss_seq_show_header(struct seq_file *seq)
 {
-        off_t pos = 0;
-        off_t len = 0;
-        int size, i, ctlr;
-        ctlr_info_t *h = (ctlr_info_t *) data;
-        drive_info_struct *drv;
-        unsigned long flags;
-        sector_t vol_sz, vol_sz_frac;
+        ctlr_info_t *h = seq->private;
+
+        seq_printf(seq, "%s: HP %s Controller\n"
+                "Board ID: 0x%08lx\n"
+                "Firmware Version: %c%c%c%c\n"
+                "IRQ: %d\n"
+                "Logical drives: %d\n"
+                "Current Q depth: %d\n"
+                "Current # commands on controller: %d\n"
+                "Max Q depth since init: %d\n"
+                "Max # commands on controller since init: %d\n"
+                "Max SG entries since init: %d\n",
+                h->devname,
+                h->product_name,
+                (unsigned long)h->board_id,
+                h->firm_ver[0], h->firm_ver[1], h->firm_ver[2],
+                h->firm_ver[3], (unsigned int)h->intr[SIMPLE_MODE_INT],
+                h->num_luns,
+                h->Qdepth, h->commands_outstanding,
+                h->maxQsinceinit, h->max_outstanding, h->maxSG);
 
-        ctlr = h->ctlr;
+#ifdef CONFIG_CISS_SCSI_TAPE
+        cciss_seq_tape_report(seq, h->ctlr);
+#endif /* CONFIG_CISS_SCSI_TAPE */
+}
+
+static void *cciss_seq_start(struct seq_file *seq, loff_t *pos)
+{
+        ctlr_info_t *h = seq->private;
+        unsigned ctlr = h->ctlr;
+        unsigned long flags;
 
         /* prevent displaying bogus info during configuration
          * or deconfiguration of a logical volume
@@ -265,115 +286,155 @@ static int cciss_proc_get_info(char *buffer, char **start, off_t offset,
         spin_lock_irqsave(CCISS_LOCK(ctlr), flags);
         if (h->busy_configuring) {
                 spin_unlock_irqrestore(CCISS_LOCK(ctlr), flags);
-                return -EBUSY;
+                return ERR_PTR(-EBUSY);
         }
         h->busy_configuring = 1;
         spin_unlock_irqrestore(CCISS_LOCK(ctlr), flags);
 
-        size = sprintf(buffer, "%s: HP %s Controller\n"
-                       "Board ID: 0x%08lx\n"
-                       "Firmware Version: %c%c%c%c\n"
-                       "IRQ: %d\n"
-                       "Logical drives: %d\n"
-                       "Max sectors: %d\n"
-                       "Current Q depth: %d\n"
-                       "Current # commands on controller: %d\n"
-                       "Max Q depth since init: %d\n"
-                       "Max # commands on controller since init: %d\n"
-                       "Max SG entries since init: %d\n\n",
-                       h->devname,
-                       h->product_name,
-                       (unsigned long)h->board_id,
-                       h->firm_ver[0], h->firm_ver[1], h->firm_ver[2],
-                       h->firm_ver[3], (unsigned int)h->intr[SIMPLE_MODE_INT],
-                       h->num_luns,
-                       h->cciss_max_sectors,
-                       h->Qdepth, h->commands_outstanding,
-                       h->maxQsinceinit, h->max_outstanding, h->maxSG);
-
-        pos += size;
-        len += size;
-        cciss_proc_tape_report(ctlr, buffer, &pos, &len);
-        for (i = 0; i <= h->highest_lun; i++) {
-
-                drv = &h->drv[i];
-                if (drv->heads == 0)
-                        continue;
+        if (*pos == 0)
+                cciss_seq_show_header(seq);
 
-                vol_sz = drv->nr_blocks;
-                vol_sz_frac = sector_div(vol_sz, ENG_GIG_FACTOR);
-                vol_sz_frac *= 100;
-                sector_div(vol_sz_frac, ENG_GIG_FACTOR);
+        return pos;
+}
+
+static int cciss_seq_show(struct seq_file *seq, void *v)
+{
+        sector_t vol_sz, vol_sz_frac;
+        ctlr_info_t *h = seq->private;
+        unsigned ctlr = h->ctlr;
+        loff_t *pos = v;
+        drive_info_struct *drv = &h->drv[*pos];
+
+        if (*pos > h->highest_lun)
+                return 0;
+
+        if (drv->heads == 0)
+                return 0;
+
+        vol_sz = drv->nr_blocks;
+        vol_sz_frac = sector_div(vol_sz, ENG_GIG_FACTOR);
+        vol_sz_frac *= 100;
+        sector_div(vol_sz_frac, ENG_GIG_FACTOR);
+
+        if (drv->raid_level > 5)
+                drv->raid_level = RAID_UNKNOWN;
+        seq_printf(seq, "cciss/c%dd%d:"
+                        "\t%4u.%02uGB\tRAID %s\n",
+                        ctlr, (int) *pos, (int)vol_sz, (int)vol_sz_frac,
+                        raid_label[drv->raid_level]);
+        return 0;
+}
+
+static void *cciss_seq_next(struct seq_file *seq, void *v, loff_t *pos)
+{
+        ctlr_info_t *h = seq->private;
+
+        if (*pos > h->highest_lun)
+                return NULL;
+        *pos += 1;
+
+        return pos;
+}
+
+static void cciss_seq_stop(struct seq_file *seq, void *v)
+{
+        ctlr_info_t *h = seq->private;
+
+        /* Only reset h->busy_configuring if we succeeded in setting
+         * it during cciss_seq_start. */
+        if (v == ERR_PTR(-EBUSY))
+                return;
 
-                if (drv->raid_level > 5)
-                        drv->raid_level = RAID_UNKNOWN;
-                size = sprintf(buffer + len, "cciss/c%dd%d:"
-                               "\t%4u.%02uGB\tRAID %s\n",
-                               ctlr, i, (int)vol_sz, (int)vol_sz_frac,
-                               raid_label[drv->raid_level]);
-                pos += size;
-                len += size;
-        }
-
-        *eof = 1;
-        *start = buffer + offset;
-        len -= offset;
-        if (len > length)
-                len = length;
         h->busy_configuring = 0;
-        return len;
 }
 
-static int
-cciss_proc_write(struct file *file, const char __user *buffer,
-                 unsigned long count, void *data)
+static struct seq_operations cciss_seq_ops = {
+        .start = cciss_seq_start,
+        .show  = cciss_seq_show,
+        .next  = cciss_seq_next,
+        .stop  = cciss_seq_stop,
+};
+
+static int cciss_seq_open(struct inode *inode, struct file *file)
 {
-        unsigned char cmd[80];
-        int len;
-#ifdef CONFIG_CISS_SCSI_TAPE
-        ctlr_info_t *h = (ctlr_info_t *) data;
-        int rc;
+        int ret = seq_open(file, &cciss_seq_ops);
+        struct seq_file *seq = file->private_data;
+
+        if (!ret)
+                seq->private = PDE(inode)->data;
+
+        return ret;
+}
+
+static ssize_t
+cciss_proc_write(struct file *file, const char __user *buf,
+                 size_t length, loff_t *ppos)
+{
+        int err;
+        char *buffer;
+
+#ifndef CONFIG_CISS_SCSI_TAPE
+        return -EINVAL;
 #endif
 
-        if (count > sizeof(cmd) - 1)
+        if (!buf || length > PAGE_SIZE - 1)
                 return -EINVAL;
-        if (copy_from_user(cmd, buffer, count))
-                return -EFAULT;
-        cmd[count] = '\0';
-        len = strlen(cmd);      // above 3 lines ensure safety
-        if (len && cmd[len - 1] == '\n')
-                cmd[--len] = '\0';
-#       ifdef CONFIG_CISS_SCSI_TAPE
-        if (strcmp("engage scsi", cmd) == 0) {
+
+        buffer = (char *)__get_free_page(GFP_KERNEL);
+        if (!buffer)
+                return -ENOMEM;
+
+        err = -EFAULT;
+        if (copy_from_user(buffer, buf, length))
+                goto out;
+        buffer[length] = '\0';
+
+#ifdef CONFIG_CISS_SCSI_TAPE
+        if (strncmp(ENGAGE_SCSI, buffer, sizeof ENGAGE_SCSI - 1) == 0) {
+                struct seq_file *seq = file->private_data;
+                ctlr_info_t *h = seq->private;
+                int rc;
+
                 rc = cciss_engage_scsi(h->ctlr);
                 if (rc != 0)
-                        return -rc;
-                return count;
-        }
+                        err = -rc;
+                else
+                        err = length;
+        } else
+#endif /* CONFIG_CISS_SCSI_TAPE */
+                err = -EINVAL;
         /* might be nice to have "disengage" too, but it's not
            safely possible. (only 1 module use count, lock issues.) */
-#       endif
-        return -EINVAL;
+
+out:
+        free_page((unsigned long)buffer);
+        return err;
 }
 
-/*
- * Get us a file in /proc/cciss that says something about each controller.
- * Create /proc/cciss if it doesn't exist yet.
- */
+static struct file_operations cciss_proc_fops = {
+        .owner   = THIS_MODULE,
+        .open    = cciss_seq_open,
+        .read    = seq_read,
+        .llseek  = seq_lseek,
+        .release = seq_release,
+        .write   = cciss_proc_write,
+};
+
 static void __devinit cciss_procinit(int i)
 {
         struct proc_dir_entry *pde;
 
-        if (proc_cciss == NULL) {
+        if (proc_cciss == NULL)
                 proc_cciss = proc_mkdir("cciss", proc_root_driver);
-                if (!proc_cciss)
-                        return;
-        }
+        if (!proc_cciss)
+                return;
+        pde = proc_create(hba[i]->devname, S_IWUSR | S_IRUSR | S_IRGRP |
+                                        S_IROTH, proc_cciss,
+                                        &cciss_proc_fops);
+        if (!pde)
+                return;
 
-        pde = create_proc_read_entry(hba[i]->devname,
-                                     S_IWUSR | S_IRUSR | S_IRGRP | S_IROTH,
-                                     proc_cciss, cciss_proc_get_info, hba[i]);
-        pde->write_proc = cciss_proc_write;
+        pde->data = hba[i];
 }
 #endif                          /* CONFIG_PROC_FS */