[PATCH] pktcdvd: Don't waste kernel memory

Allocate memory for read-gathering at open time, when it is known just how
much memory is needed.  This avoids wasting kernel memory when the real packet
size is smaller than the maximum packet size supported by the driver.  This is
always the case when using DVD discs.

Signed-off-by: Peter Osterlund <petero2@telia.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/drivers/block/Kconfig b/drivers/block/Kconfig
index db6818fdf15dfccd3608e1a9ffa60202d5841c9b..8b133167740768c6ac96071a356a7c8fd1046ac6 100644 (file)
--- a/drivers/block/Kconfig
+++ b/drivers/block/Kconfig
@@ -433,8 +433,8 @@ config CDROM_PKTCDVD_BUFFERS
          This controls the maximum number of active concurrent packets. More
          concurrent packets can increase write performance, but also require
          more memory. Each concurrent packet will require approximately 64Kb
-         of non-swappable kernel memory, memory which will be allocated at
-         pktsetup time.
+         of non-swappable kernel memory, memory which will be allocated when
+         a disc is opened for writing.
 
 config CDROM_PKTCDVD_WCACHE
        bool "Enable write caching (EXPERIMENTAL)"

diff --git a/drivers/block/pktcdvd.c b/drivers/block/pktcdvd.c
index cd16813effc5f06182f36203c8317c104840f23a..4e7dbcc425ff69d7f1f3c851e47d7ed5c60351b6 100644 (file)
--- a/drivers/block/pktcdvd.c
+++ b/drivers/block/pktcdvd.c
@@ -129,7 +129,7 @@ static struct bio *pkt_bio_alloc(int nr_iovecs)
 /*
  * Allocate a packet_data struct
  */
-static struct packet_data *pkt_alloc_packet_data(void)
+static struct packet_data *pkt_alloc_packet_data(int frames)
 {
        int i;
        struct packet_data *pkt;
@@ -138,11 +138,12 @@ static struct packet_data *pkt_alloc_packet_data(void)
        if (!pkt)
                goto no_pkt;
 
-       pkt->w_bio = pkt_bio_alloc(PACKET_MAX_SIZE);
+       pkt->frames = frames;
+       pkt->w_bio = pkt_bio_alloc(frames);
        if (!pkt->w_bio)
                goto no_bio;
 
-       for (i = 0; i < PAGES_PER_PACKET; i++) {
+       for (i = 0; i < frames / FRAMES_PER_PAGE; i++) {
                pkt->pages[i] = alloc_page(GFP_KERNEL|__GFP_ZERO);
                if (!pkt->pages[i])
                        goto no_page;
@@ -150,7 +151,7 @@ static struct packet_data *pkt_alloc_packet_data(void)
 
        spin_lock_init(&pkt->lock);
 
-       for (i = 0; i < PACKET_MAX_SIZE; i++) {
+       for (i = 0; i < frames; i++) {
                struct bio *bio = pkt_bio_alloc(1);
                if (!bio)
                        goto no_rd_bio;
@@ -160,14 +161,14 @@ static struct packet_data *pkt_alloc_packet_data(void)
        return pkt;
 
 no_rd_bio:
-       for (i = 0; i < PACKET_MAX_SIZE; i++) {
+       for (i = 0; i < frames; i++) {
                struct bio *bio = pkt->r_bios[i];
                if (bio)
                        bio_put(bio);
        }
 
 no_page:
-       for (i = 0; i < PAGES_PER_PACKET; i++)
+       for (i = 0; i < frames / FRAMES_PER_PAGE; i++)
                if (pkt->pages[i])
                        __free_page(pkt->pages[i]);
        bio_put(pkt->w_bio);
@@ -184,12 +185,12 @@ static void pkt_free_packet_data(struct packet_data *pkt)
 {
        int i;
 
-       for (i = 0; i < PACKET_MAX_SIZE; i++) {
+       for (i = 0; i < pkt->frames; i++) {
                struct bio *bio = pkt->r_bios[i];
                if (bio)
                        bio_put(bio);
        }
-       for (i = 0; i < PAGES_PER_PACKET; i++)
+       for (i = 0; i < pkt->frames / FRAMES_PER_PAGE; i++)
                __free_page(pkt->pages[i]);
        bio_put(pkt->w_bio);
        kfree(pkt);
@@ -204,17 +205,17 @@ static void pkt_shrink_pktlist(struct pktcdvd_device *pd)
        list_for_each_entry_safe(pkt, next, &pd->cdrw.pkt_free_list, list) {
                pkt_free_packet_data(pkt);
        }
+       INIT_LIST_HEAD(&pd->cdrw.pkt_free_list);
 }
 
 static int pkt_grow_pktlist(struct pktcdvd_device *pd, int nr_packets)
 {
        struct packet_data *pkt;
 
-       INIT_LIST_HEAD(&pd->cdrw.pkt_free_list);
-       INIT_LIST_HEAD(&pd->cdrw.pkt_active_list);
-       spin_lock_init(&pd->cdrw.active_list_lock);
+       BUG_ON(!list_empty(&pd->cdrw.pkt_free_list));
+
        while (nr_packets > 0) {
-               pkt = pkt_alloc_packet_data();
+               pkt = pkt_alloc_packet_data(pd->settings.size >> 2);
                if (!pkt) {
                        pkt_shrink_pktlist(pd);
                        return 0;
@@ -949,7 +950,7 @@ try_next_bio:
 
        pd->current_sector = zone + pd->settings.size;
        pkt->sector = zone;
-       pkt->frames = pd->settings.size >> 2;
+       BUG_ON(pkt->frames != pd->settings.size >> 2);
        pkt->write_size = 0;
 
        /*
@@ -1985,8 +1986,14 @@ static int pkt_open_dev(struct pktcdvd_device *pd, int write)
        if ((ret = pkt_set_segment_merging(pd, q)))
                goto out_unclaim;
 
-       if (write)
+       if (write) {
+               if (!pkt_grow_pktlist(pd, CONFIG_CDROM_PKTCDVD_BUFFERS)) {
+                       printk("pktcdvd: not enough memory for buffers\n");
+                       ret = -ENOMEM;
+                       goto out_unclaim;
+               }
                printk("pktcdvd: %lukB available on disc\n", lba << 1);
+       }
 
        return 0;
 
@@ -2012,6 +2019,8 @@ static void pkt_release_dev(struct pktcdvd_device *pd, int flush)
        pkt_set_speed(pd, MAX_SPEED, MAX_SPEED);
        bd_release(pd->bdev);
        blkdev_put(pd->bdev);
+
+       pkt_shrink_pktlist(pd);
 }
 
 static struct pktcdvd_device *pkt_find_dev_from_minor(int dev_minor)
@@ -2377,12 +2386,6 @@ static int pkt_new_dev(struct pktcdvd_device *pd, dev_t dev)
        /* This is safe, since we have a reference from open(). */
        __module_get(THIS_MODULE);
 
-       if (!pkt_grow_pktlist(pd, CONFIG_CDROM_PKTCDVD_BUFFERS)) {
-               printk("pktcdvd: not enough memory for buffers\n");
-               ret = -ENOMEM;
-               goto out_mem;
-       }
-
        pd->bdev = bdev;
        set_blocksize(bdev, CD_FRAMESIZE);
 
@@ -2393,7 +2396,7 @@ static int pkt_new_dev(struct pktcdvd_device *pd, dev_t dev)
        if (IS_ERR(pd->cdrw.thread)) {
                printk("pktcdvd: can't start kernel thread\n");
                ret = -ENOMEM;
-               goto out_thread;
+               goto out_mem;
        }
 
        proc = create_proc_entry(pd->name, 0, pkt_proc);
@@ -2404,8 +2407,6 @@ static int pkt_new_dev(struct pktcdvd_device *pd, dev_t dev)
        DPRINTK("pktcdvd: writer %s mapped to %s\n", pd->name, bdevname(bdev, b));
        return 0;
 
-out_thread:
-       pkt_shrink_pktlist(pd);
 out_mem:
        blkdev_put(bdev);
        /* This is safe: open() is still holding a reference. */
@@ -2501,6 +2502,10 @@ static int pkt_setup_dev(struct pkt_ctrl_command *ctrl_cmd)
                goto out_mem;
        pd->disk = disk;
 
+       INIT_LIST_HEAD(&pd->cdrw.pkt_free_list);
+       INIT_LIST_HEAD(&pd->cdrw.pkt_active_list);
+       spin_lock_init(&pd->cdrw.active_list_lock);
+
        spin_lock_init(&pd->lock);
        spin_lock_init(&pd->iosched.lock);
        sprintf(pd->name, "pktcdvd%d", idx);
@@ -2565,8 +2570,6 @@ static int pkt_remove_dev(struct pkt_ctrl_command *ctrl_cmd)
 
        blkdev_put(pd->bdev);
 
-       pkt_shrink_pktlist(pd);
-
        remove_proc_entry(pd->name, pkt_proc);
        DPRINTK("pktcdvd: writer %s unmapped\n", pd->name);
 

diff --git a/include/linux/pktcdvd.h b/include/linux/pktcdvd.h
index d1c9c4a86e52bb55886938618a195744a9ae4782..1623da88d6fedd15cc400137b2ca32c18b25f859 100644 (file)
--- a/include/linux/pktcdvd.h
+++ b/include/linux/pktcdvd.h
@@ -170,7 +170,7 @@ struct packet_iosched
 #error "PAGE_SIZE must be a multiple of CD_FRAMESIZE"
 #endif
 #define PACKET_MAX_SIZE                32
-#define PAGES_PER_PACKET       (PACKET_MAX_SIZE * CD_FRAMESIZE / PAGE_SIZE)
+#define FRAMES_PER_PAGE                (PAGE_SIZE / CD_FRAMESIZE)
 #define PACKET_MAX_SECTORS     (PACKET_MAX_SIZE * CD_FRAMESIZE >> 9)
 
 enum packet_data_state {
@@ -219,7 +219,7 @@ struct packet_data
        atomic_t                io_errors;      /* Number of read/write errors during IO */
 
        struct bio              *r_bios[PACKET_MAX_SIZE]; /* bios to use during data gathering */
-       struct page             *pages[PAGES_PER_PACKET];
+       struct page             *pages[PACKET_MAX_SIZE / FRAMES_PER_PAGE];
 
        int                     cache_valid;    /* If non-zero, the data for the zone defined */
                                                /* by the sector variable is completely cached */