ps3flash: Cache the last accessed FLASH chunk
[pandora-kernel.git] / drivers / char / ps3flash.c
index f7f21f4..d884d31 100644 (file)
 
 struct ps3flash_private {
        struct mutex mutex;     /* Bounce buffer mutex */
+       u64 chunk_sectors;
+       int tag;                /* Start sector of buffer, -1 if invalid */
+       bool dirty;
 };
 
 static struct ps3_storage_device *ps3flash_dev;
 
-static ssize_t ps3flash_read_write_sectors(struct ps3_storage_device *dev,
-                                          u64 lpar, u64 start_sector,
-                                          u64 sectors, int write)
+static int ps3flash_read_write_sectors(struct ps3_storage_device *dev,
+                                      u64 lpar, u64 start_sector, u64 sectors,
+                                      int write)
 {
        u64 res = ps3stor_read_write_sectors(dev, lpar, start_sector, sectors,
                                             write);
@@ -48,33 +51,55 @@ static ssize_t ps3flash_read_write_sectors(struct ps3_storage_device *dev,
                        __LINE__, write ? "write" : "read", res);
                return -EIO;
        }
-       return sectors;
+       return 0;
 }
 
-static ssize_t ps3flash_read_sectors(struct ps3_storage_device *dev,
-                                    u64 start_sector, u64 sectors,
-                                    unsigned int sector_offset)
+static int ps3flash_writeback(struct ps3_storage_device *dev)
 {
-       u64 max_sectors, lpar;
+       struct ps3flash_private *priv = ps3_system_bus_get_drvdata(&dev->sbd);
+       int res;
 
-       max_sectors = dev->bounce_size / dev->blk_size;
-       if (sectors > max_sectors) {
-               dev_dbg(&dev->sbd.core, "%s:%u Limiting sectors to %llu\n",
-                       __func__, __LINE__, max_sectors);
-               sectors = max_sectors;
-       }
+       if (!priv->dirty || priv->tag < 0)
+               return 0;
+
+       res = ps3flash_read_write_sectors(dev, dev->bounce_lpar, priv->tag,
+                                         priv->chunk_sectors, 1);
+       if (res)
+               return res;
 
-       lpar = dev->bounce_lpar + sector_offset * dev->blk_size;
-       return ps3flash_read_write_sectors(dev, lpar, start_sector, sectors,
-                                          0);
+       priv->dirty = false;
+       return 0;
 }
 
-static ssize_t ps3flash_write_chunk(struct ps3_storage_device *dev,
-                                   u64 start_sector)
+static int ps3flash_fetch(struct ps3_storage_device *dev, u64 start_sector,
+                         u64 sectors)
 {
-       u64 sectors = dev->bounce_size / dev->blk_size;
-       return ps3flash_read_write_sectors(dev, dev->bounce_lpar, start_sector,
-                                         sectors, 1);
+       struct ps3flash_private *priv = ps3_system_bus_get_drvdata(&dev->sbd);
+       unsigned int tag, offset;
+       u64 lpar;
+       int res;
+
+       offset = start_sector % priv->chunk_sectors;
+       tag = start_sector - offset;
+       if (tag == priv->tag)
+               return 0;
+
+       res = ps3flash_writeback(dev);
+       if (res)
+               return res;
+
+       priv->tag = -1;
+
+       lpar = dev->bounce_lpar + offset * dev->blk_size;
+       res = ps3flash_read_write_sectors(dev, lpar, start_sector, sectors, 0);
+       if (res)
+               return res;
+
+       /* We don't bother caching reads smaller than the chunk size */
+       if (sectors == priv->chunk_sectors)
+               priv->tag = tag;
+
+       return 0;
 }
 
 static loff_t ps3flash_llseek(struct file *file, loff_t offset, int origin)
@@ -109,8 +134,8 @@ static ssize_t ps3flash_read(char __user *userbuf, void *kernelbuf,
 {
        struct ps3_storage_device *dev = ps3flash_dev;
        struct ps3flash_private *priv = ps3_system_bus_get_drvdata(&dev->sbd);
-       u64 size, start_sector, end_sector, offset;
-       ssize_t sectors_read;
+       u64 size, start_sector, end_sector, offset, sectors;
+       int res;
        size_t remaining, n;
        const void *src;
 
@@ -130,30 +155,29 @@ static ssize_t ps3flash_read(char __user *userbuf, void *kernelbuf,
        }
 
        start_sector = *pos / dev->blk_size;
-       offset = *pos % dev->blk_size;
+       offset = *pos % dev->bounce_size;
        end_sector = DIV_ROUND_UP(*pos + count, dev->blk_size);
 
        remaining = count;
        do {
+               sectors = min(end_sector - start_sector,
+                             priv->chunk_sectors -
+                             start_sector % priv->chunk_sectors);
+
                mutex_lock(&priv->mutex);
 
-               sectors_read = ps3flash_read_sectors(dev, start_sector,
-                                                    end_sector-start_sector,
-                                                    0);
-               if (sectors_read < 0) {
-                       mutex_unlock(&priv->mutex);
+               res = ps3flash_fetch(dev, start_sector, sectors);
+               if (res)
                        goto fail;
-               }
 
-               n = min_t(u64, remaining, sectors_read*dev->blk_size-offset);
-               src = dev->bounce_buf+offset;
+               n = min_t(u64, remaining, dev->bounce_size - offset);
+               src = dev->bounce_buf + offset;
                dev_dbg(&dev->sbd.core,
                        "%s:%u: copy %lu bytes from 0x%p to U0x%p/K0x%p\n",
                        __func__, __LINE__, n, src, userbuf, kernelbuf);
                if (userbuf) {
                        if (copy_to_user(userbuf, src, n)) {
-                               mutex_unlock(&priv->mutex);
-                               sectors_read = -EFAULT;
+                               res = -EFAULT;
                                goto fail;
                        }
                        userbuf += n;
@@ -167,14 +191,15 @@ static ssize_t ps3flash_read(char __user *userbuf, void *kernelbuf,
 
                *pos += n;
                remaining -= n;
-               start_sector += sectors_read;
+               start_sector += sectors;
                offset = 0;
        } while (remaining > 0);
 
        return count;
 
 fail:
-       return sectors_read;
+       mutex_unlock(&priv->mutex);
+       return res;
 }
 
 static ssize_t ps3flash_write(const char __user *userbuf,
@@ -182,11 +207,9 @@ static ssize_t ps3flash_write(const char __user *userbuf,
 {
        struct ps3_storage_device *dev = ps3flash_dev;
        struct ps3flash_private *priv = ps3_system_bus_get_drvdata(&dev->sbd);
-       u64 size, chunk_sectors, start_write_sector, end_write_sector,
-           end_read_sector, start_read_sector, head, tail, offset;
-       ssize_t res;
+       u64 size, sector, offset;
+       int res = 0;
        size_t remaining, n;
-       unsigned int sec_off;
        void *dst;
 
        dev_dbg(&dev->sbd.core,
@@ -204,71 +227,23 @@ static ssize_t ps3flash_write(const char __user *userbuf,
                count = size - *pos;
        }
 
-       chunk_sectors = dev->bounce_size / dev->blk_size;
-
-       start_write_sector = *pos / dev->bounce_size * chunk_sectors;
+       sector = *pos / dev->bounce_size * priv->chunk_sectors;
        offset = *pos % dev->bounce_size;
-       end_write_sector = DIV_ROUND_UP(*pos + count, dev->bounce_size) *
-                          chunk_sectors;
-
-       end_read_sector = DIV_ROUND_UP(*pos, dev->blk_size);
-       start_read_sector = (*pos + count) / dev->blk_size;
-
-       /*
-        * As we have to write in 256 KiB chunks, while we can read in blk_size
-        * (usually 512 bytes) chunks, we perform the following steps:
-        *   1. Read from start_write_sector to end_read_sector ("head")
-        *   2. Read from start_read_sector to end_write_sector ("tail")
-        *   3. Copy data to buffer
-        *   4. Write from start_write_sector to end_write_sector
-        * All of this is complicated by using only one 256 KiB bounce buffer.
-        */
-
-       head = end_read_sector - start_write_sector;
-       tail = end_write_sector - start_read_sector;
 
        remaining = count;
        do {
+               n = min_t(u64, remaining, dev->bounce_size - offset);
+
                mutex_lock(&priv->mutex);
 
-               if (end_read_sector >= start_read_sector) {
-                       /* Merge head and tail */
-                       dev_dbg(&dev->sbd.core,
-                               "Merged head and tail: %llu sectors at %llu\n",
-                               chunk_sectors, start_write_sector);
-                       res = ps3flash_read_sectors(dev, start_write_sector,
-                                                   chunk_sectors, 0);
-                       if (res < 0)
-                               goto fail;
-               } else {
-                       if (head) {
-                               /* Read head */
-                               dev_dbg(&dev->sbd.core,
-                                       "head: %llu sectors at %llu\n", head,
-                                       start_write_sector);
-                               res = ps3flash_read_sectors(dev,
-                                                           start_write_sector,
-                                                           head, 0);
-                               if (res < 0)
-                                       goto fail;
-                       }
-                       if (start_read_sector <
-                           start_write_sector+chunk_sectors) {
-                               /* Read tail */
-                               dev_dbg(&dev->sbd.core,
-                                       "tail: %llu sectors at %llu\n", tail,
-                                       start_read_sector);
-                               sec_off = start_read_sector-start_write_sector;
-                               res = ps3flash_read_sectors(dev,
-                                                           start_read_sector,
-                                                           tail, sec_off);
-                               if (res < 0)
-                                       goto fail;
-                       }
-               }
+               if (n != dev->bounce_size)
+                       res = ps3flash_fetch(dev, sector, priv->chunk_sectors);
+               else if (sector != priv->tag)
+                       res = ps3flash_writeback(dev);
+               if (res)
+                       goto fail;
 
-               n = min_t(u64, remaining, dev->bounce_size-offset);
-               dst = dev->bounce_buf+offset;
+               dst = dev->bounce_buf + offset;
                dev_dbg(&dev->sbd.core,
                        "%s:%u: copy %lu bytes from U0x%p/K0x%p to 0x%p\n",
                        __func__, __LINE__, n, userbuf, kernelbuf, dst);
@@ -284,16 +259,14 @@ static ssize_t ps3flash_write(const char __user *userbuf,
                        kernelbuf += n;
                }
 
-               res = ps3flash_write_chunk(dev, start_write_sector);
-               if (res < 0)
-                       goto fail;
+               priv->tag = sector;
+               priv->dirty = true;
 
                mutex_unlock(&priv->mutex);
 
                *pos += n;
                remaining -= n;
-               start_write_sector += chunk_sectors;
-               head = 0;
+               sector += priv->chunk_sectors;
                offset = 0;
        } while (remaining > 0);
 
@@ -324,9 +297,31 @@ static ssize_t ps3flash_kernel_read(void *buf, size_t count, loff_t pos)
 static ssize_t ps3flash_kernel_write(const void *buf, size_t count,
                                     loff_t pos)
 {
-       return ps3flash_write(NULL, buf, count, &pos);
+       ssize_t res;
+       int wb;
+
+       res = ps3flash_write(NULL, buf, count, &pos);
+       if (res < 0)
+               return res;
+
+       /* Make kernel writes synchronous */
+       wb = ps3flash_writeback(ps3flash_dev);
+       if (wb)
+               return wb;
+
+       return res;
 }
 
+static int ps3flash_flush(struct file *file, fl_owner_t id)
+{
+       return ps3flash_writeback(ps3flash_dev);
+}
+
+static int ps3flash_fsync(struct file *file, struct dentry *dentry,
+                         int datasync)
+{
+       return ps3flash_writeback(ps3flash_dev);
+}
 
 static irqreturn_t ps3flash_interrupt(int irq, void *data)
 {
@@ -356,6 +351,8 @@ static const struct file_operations ps3flash_fops = {
        .llseek = ps3flash_llseek,
        .read   = ps3flash_user_read,
        .write  = ps3flash_user_write,
+       .flush  = ps3flash_flush,
+       .fsync  = ps3flash_fsync,
 };
 
 static const struct ps3_os_area_flash_ops ps3flash_kernel_ops = {
@@ -411,9 +408,11 @@ static int __devinit ps3flash_probe(struct ps3_system_bus_device *_dev)
 
        ps3_system_bus_set_drvdata(&dev->sbd, priv);
        mutex_init(&priv->mutex);
+       priv->tag = -1;
 
        dev->bounce_size = ps3flash_bounce_buffer.size;
        dev->bounce_buf = ps3flash_bounce_buffer.address;
+       priv->chunk_sectors = dev->bounce_size / dev->blk_size;
 
        error = ps3stor_setup(dev, ps3flash_interrupt);
        if (error)