[PATCH 1/2 v2] UBI: Add initial support for scatter gather
Richard Weinberger
richard at nod.at
Sat Jan 10 13:52:13 PST 2015
Adds a new set of functions to deal with scatter gather.
ubi_eba_read_leb_sg() will read from a LEB into a scatter gather list.
The new data structure struct ubi_sgl will be used within UBI to
hold the scatter gather list itself and metadata to have a cursor
within the list.
Signed-off-by: Richard Weinberger <richard at nod.at>
Tested-by: Ezequiel Garcia <ezequiel at vanguardiasur.com.ar>
---
drivers/mtd/ubi/eba.c | 56 +++++++++++++++++++++++++++++
drivers/mtd/ubi/kapi.c | 95 +++++++++++++++++++++++++++++++++++++++++--------
drivers/mtd/ubi/ubi.h | 3 ++
include/linux/mtd/ubi.h | 46 ++++++++++++++++++++++++
4 files changed, 185 insertions(+), 15 deletions(-)
diff --git a/drivers/mtd/ubi/eba.c b/drivers/mtd/ubi/eba.c
index b698534..0aaf707 100644
--- a/drivers/mtd/ubi/eba.c
+++ b/drivers/mtd/ubi/eba.c
@@ -481,6 +481,62 @@ out_unlock:
}
/**
+ * ubi_eba_read_leb_sg - read data into a scatter gather list.
+ * @ubi: UBI device description object
+ * @vol: volume description object
+ * @lnum: logical eraseblock number
+ * @sgl: UBI scatter gather list to store the read data
+ * @offset: offset from where to read
+ * @len: how many bytes to read
+ * @check: data CRC check flag
+ *
+ * This function works exactly like ubi_eba_read_leb(). But instead of
+ * storing the read data into a buffer it writes to an UBI scatter gather
+ * list.
+ */
+int ubi_eba_read_leb_sg(struct ubi_device *ubi, struct ubi_volume *vol,
+ struct ubi_sgl *sgl, int lnum, int offset, int len,
+ int check)
+{
+ int to_read;
+ int ret;
+ struct scatterlist *sg;
+
+ for (;;) {
+ ubi_assert(sgl->list_pos < UBI_MAX_SG_COUNT);
+ sg = &sgl->sg[sgl->list_pos];
+ if (len < sg->length - sgl->page_pos)
+ to_read = len;
+ else
+ to_read = sg->length - sgl->page_pos;
+
+ ret = ubi_eba_read_leb(ubi, vol, lnum,
+ sg_virt(sg) + sgl->page_pos, offset,
+ to_read, check);
+ if (ret < 0)
+ goto out;
+
+ offset += to_read;
+ len -= to_read;
+ if (!len) {
+ sgl->page_pos += to_read;
+ if (sgl->page_pos == sg->length) {
+ sgl->list_pos++;
+ sgl->page_pos = 0;
+ }
+
+ break;
+ }
+
+ sgl->list_pos++;
+ sgl->page_pos = 0;
+ }
+
+out:
+ return ret;
+}
+
+/**
* recover_peb - recover from write failure.
* @ubi: UBI device description object
* @pnum: the physical eraseblock to recover
diff --git a/drivers/mtd/ubi/kapi.c b/drivers/mtd/ubi/kapi.c
index f3bab66..d0055a2 100644
--- a/drivers/mtd/ubi/kapi.c
+++ b/drivers/mtd/ubi/kapi.c
@@ -355,6 +355,43 @@ void ubi_close_volume(struct ubi_volume_desc *desc)
EXPORT_SYMBOL_GPL(ubi_close_volume);
/**
+ * leb_read_sanity_check - does sanity checks on read requests.
+ * @desc: volume descriptor
+ * @lnum: logical eraseblock number to read from
+ * @offset: offset within the logical eraseblock to read from
+ * @len: how many bytes to read
+ *
+ * This function is used by ubi_leb_read() and ubi_leb_read_sg()
+ * to perfrom sanity checks.
+ */
+static int leb_read_sanity_check(struct ubi_volume_desc *desc, int lnum,
+ int offset, int len)
+{
+ struct ubi_volume *vol = desc->vol;
+ struct ubi_device *ubi = vol->ubi;
+ int vol_id = vol->vol_id;
+
+ if (vol_id < 0 || vol_id >= ubi->vtbl_slots || lnum < 0 ||
+ lnum >= vol->used_ebs || offset < 0 || len < 0 ||
+ offset + len > vol->usable_leb_size)
+ return -EINVAL;
+
+ if (vol->vol_type == UBI_STATIC_VOLUME) {
+ if (vol->used_ebs == 0)
+ /* Empty static UBI volume */
+ return 0;
+ if (lnum == vol->used_ebs - 1 &&
+ offset + len > vol->last_eb_bytes)
+ return -EINVAL;
+ }
+
+ if (vol->upd_marker)
+ return -EBADF;
+
+ return 0;
+}
+
+/**
* ubi_leb_read - read data.
* @desc: volume descriptor
* @lnum: logical eraseblock number to read from
@@ -390,22 +427,10 @@ int ubi_leb_read(struct ubi_volume_desc *desc, int lnum, char *buf, int offset,
dbg_gen("read %d bytes from LEB %d:%d:%d", len, vol_id, lnum, offset);
- if (vol_id < 0 || vol_id >= ubi->vtbl_slots || lnum < 0 ||
- lnum >= vol->used_ebs || offset < 0 || len < 0 ||
- offset + len > vol->usable_leb_size)
- return -EINVAL;
-
- if (vol->vol_type == UBI_STATIC_VOLUME) {
- if (vol->used_ebs == 0)
- /* Empty static UBI volume */
- return 0;
- if (lnum == vol->used_ebs - 1 &&
- offset + len > vol->last_eb_bytes)
- return -EINVAL;
- }
+ err = leb_read_sanity_check(desc, lnum, offset, len);
+ if (err < 0)
+ return err;
- if (vol->upd_marker)
- return -EBADF;
if (len == 0)
return 0;
@@ -419,6 +444,46 @@ int ubi_leb_read(struct ubi_volume_desc *desc, int lnum, char *buf, int offset,
}
EXPORT_SYMBOL_GPL(ubi_leb_read);
+
+/**
+ * ubi_leb_read_sg - read data into a scatter gather list.
+ * @desc: volume descriptor
+ * @lnum: logical eraseblock number to read from
+ * @buf: buffer where to store the read data
+ * @offset: offset within the logical eraseblock to read from
+ * @len: how many bytes to read
+ * @check: whether UBI has to check the read data's CRC or not.
+ *
+ * This function works exactly like ubi_leb_read_sg(). But instead of
+ * storing the read data into a buffer it writes to an UBI scatter gather
+ * list.
+ */
+int ubi_leb_read_sg(struct ubi_volume_desc *desc, int lnum, struct ubi_sgl *sgl,
+ int offset, int len, int check)
+{
+ struct ubi_volume *vol = desc->vol;
+ struct ubi_device *ubi = vol->ubi;
+ int err, vol_id = vol->vol_id;
+
+ dbg_gen("read %d bytes from LEB %d:%d:%d", len, vol_id, lnum, offset);
+
+ err = leb_read_sanity_check(desc, lnum, offset, len);
+ if (err < 0)
+ return err;
+
+ if (len == 0)
+ return 0;
+
+ err = ubi_eba_read_leb_sg(ubi, vol, sgl, lnum, offset, len, check);
+ if (err && mtd_is_eccerr(err) && vol->vol_type == UBI_STATIC_VOLUME) {
+ ubi_warn(ubi, "mark volume %d as corrupted", vol_id);
+ vol->corrupted = 1;
+ }
+
+ return err;
+}
+EXPORT_SYMBOL_GPL(ubi_leb_read_sg);
+
/**
* ubi_leb_write - write data.
* @desc: volume descriptor
diff --git a/drivers/mtd/ubi/ubi.h b/drivers/mtd/ubi/ubi.h
index ee7ac0b..a5283cf 100644
--- a/drivers/mtd/ubi/ubi.h
+++ b/drivers/mtd/ubi/ubi.h
@@ -791,6 +791,9 @@ int ubi_eba_unmap_leb(struct ubi_device *ubi, struct ubi_volume *vol,
int lnum);
int ubi_eba_read_leb(struct ubi_device *ubi, struct ubi_volume *vol, int lnum,
void *buf, int offset, int len, int check);
+int ubi_eba_read_leb_sg(struct ubi_device *ubi, struct ubi_volume *vol,
+ struct ubi_sgl *sgl, int lnum, int offset, int len,
+ int check);
int ubi_eba_write_leb(struct ubi_device *ubi, struct ubi_volume *vol, int lnum,
const void *buf, int offset, int len);
int ubi_eba_write_leb_st(struct ubi_device *ubi, struct ubi_volume *vol,
diff --git a/include/linux/mtd/ubi.h b/include/linux/mtd/ubi.h
index c3918a0..3d5916d 100644
--- a/include/linux/mtd/ubi.h
+++ b/include/linux/mtd/ubi.h
@@ -23,11 +23,16 @@
#include <linux/ioctl.h>
#include <linux/types.h>
+#include <linux/scatterlist.h>
#include <mtd/ubi-user.h>
/* All voumes/LEBs */
#define UBI_ALL -1
+/* Maximum number of scatter gather list entries,
+ * we use only 64 to have a lower memory foot print. */
+#define UBI_MAX_SG_COUNT 64
+
/*
* enum ubi_open_mode - UBI volume open mode constants.
*
@@ -116,6 +121,35 @@ struct ubi_volume_info {
};
/**
+ * struct ubi_sgl - UBI scatter gather list data structure.
+ * @list_pos: current position in @sg[]
+ * @page_pos: current position in @sg[@list_pos]
+ * @sg: the scatter gather list itself
+ *
+ * ubi_sgl is a wrapper around a scatter list which keeps track of the
+ * current position in the list and the current list item such that
+ * it can be used across multiple ubi_leb_read_sg() calls.
+ */
+struct ubi_sgl {
+ int list_pos;
+ int page_pos;
+ struct scatterlist sg[UBI_MAX_SG_COUNT];
+};
+
+/**
+ * ubi_sgl_init - initialize an UBI scatter gather list data structure.
+ * @usgl: the UBI scatter gather struct itself
+ *
+ * Please note that you still have to use sg_init_table() or any adequate
+ * function to initialize the unterlaying struct scatterlist.
+ */
+static inline void ubi_sgl_init(struct ubi_sgl *usgl)
+{
+ usgl->list_pos = 0;
+ usgl->page_pos = 0;
+}
+
+/**
* struct ubi_device_info - UBI device description data structure.
* @ubi_num: ubi device number
* @leb_size: logical eraseblock size on this UBI device
@@ -210,6 +244,8 @@ int ubi_unregister_volume_notifier(struct notifier_block *nb);
void ubi_close_volume(struct ubi_volume_desc *desc);
int ubi_leb_read(struct ubi_volume_desc *desc, int lnum, char *buf, int offset,
int len, int check);
+int ubi_leb_read_sg(struct ubi_volume_desc *desc, int lnum, struct ubi_sgl *sgl,
+ int offset, int len, int check);
int ubi_leb_write(struct ubi_volume_desc *desc, int lnum, const void *buf,
int offset, int len);
int ubi_leb_change(struct ubi_volume_desc *desc, int lnum, const void *buf,
@@ -230,4 +266,14 @@ static inline int ubi_read(struct ubi_volume_desc *desc, int lnum, char *buf,
{
return ubi_leb_read(desc, lnum, buf, offset, len, 0);
}
+
+/*
+ * This function is the same as the 'ubi_leb_read_sg()' function, but it does
+ * not provide the checking capability.
+ */
+static inline int ubi_read_sg(struct ubi_volume_desc *desc, int lnum,
+ struct ubi_sgl *sgl, int offset, int len)
+{
+ return ubi_leb_read_sg(desc, lnum, sgl, offset, len, 0);
+}
#endif /* !__LINUX_UBI_H__ */
--
1.8.4.5
More information about the linux-mtd
mailing list