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111 lines
3.0 KiB
111 lines
3.0 KiB
From: Jeff Mahoney <jeffm@suse.com>
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Subject: [PATCH] scsi: iterate over devices individually for /proc/scsi/scsi
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References: 263731
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Patch-mainline: Probably never, hch wants to kill /proc/scsi/scsi anyway.
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On systems with very large numbers (> 1600 or so) of SCSI devices,
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cat /proc/scsi/scsi ends up failing with -ENOMEM. This is due to
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the show routine simply iterating over all of the devices with
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bus_for_each_dev(), and trying to dump all of them into the buffer
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at the same time. On my test system (using scsi_debug with 4064 devices),
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the output ends up being ~ 632k, far more than kmalloc will typically allow.
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This patch defines its own seq_file opreations to iterate over the scsi
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devices.The result is that each show() operation only dumps ~ 180 bytes
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into the buffer at a time so we don't run out of memory.
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If the "Attached devices" header isn't required, we can dump the
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sfile->private bit completely.
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Signed-off-by: Jeff Mahoney <jeffm@suse.com>
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---
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drivers/scsi/scsi_proc.c | 58 ++++++++++++++++++++++++++++++++++++++++++-----
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1 file changed, 52 insertions(+), 6 deletions(-)
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--- a/drivers/scsi/scsi_proc.c
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+++ b/drivers/scsi/scsi_proc.c
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@@ -386,13 +386,59 @@ static ssize_t proc_scsi_write(struct fi
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* @s: output goes here
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* @p: not used
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*/
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-static int proc_scsi_show(struct seq_file *s, void *p)
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+static int always_match(struct device *dev, void *data)
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{
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- seq_printf(s, "Attached devices:\n");
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- bus_for_each_dev(&scsi_bus_type, NULL, s, proc_print_scsidevice);
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- return 0;
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+ return 1;
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}
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+static inline struct device *next_scsi_device(struct device *start)
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+{
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+ struct device *next = bus_find_device(&scsi_bus_type, start, NULL,
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+ always_match);
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+ put_device(start);
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+ return next;
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+}
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+
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+static void *scsi_seq_start(struct seq_file *sfile, loff_t *pos)
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+{
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+ struct device *dev = NULL;
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+ loff_t n = *pos;
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+
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+ while ((dev = next_scsi_device(dev))) {
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+ if (!n--)
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+ break;
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+ sfile->private++;
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+ }
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+ return dev;
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+}
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+
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+static void *scsi_seq_next(struct seq_file *sfile, void *v, loff_t *pos)
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+{
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+ (*pos)++;
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+ sfile->private++;
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+ return next_scsi_device(v);
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+}
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+
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+static void scsi_seq_stop(struct seq_file *sfile, void *v)
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+{
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+ put_device(v);
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+}
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+
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+static int scsi_seq_show(struct seq_file *sfile, void *dev)
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+{
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+ if (!sfile->private)
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+ seq_puts(sfile, "Attached devices:\n");
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+
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+ return proc_print_scsidevice(dev, sfile);
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+}
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+
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+static struct seq_operations scsi_seq_ops = {
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+ .start = scsi_seq_start,
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+ .next = scsi_seq_next,
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+ .stop = scsi_seq_stop,
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+ .show = scsi_seq_show
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+};
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+
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/**
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* proc_scsi_open - glue function
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* @inode: not used
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@@ -406,7 +452,7 @@ static int proc_scsi_open(struct inode *
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* We don't really need this for the write case but it doesn't
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* harm either.
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*/
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- return single_open(file, proc_scsi_show, NULL);
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+ return seq_open(file, &scsi_seq_ops);
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}
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static const struct file_operations proc_scsi_operations = {
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@@ -415,7 +461,7 @@ static const struct file_operations proc
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.read = seq_read,
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.write = proc_scsi_write,
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.llseek = seq_lseek,
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- .release = single_release,
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+ .release = seq_release,
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};
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/**
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