[PATCH] ubi: fastmap: Check each mapping only once

Martin Kepplinger
2018-11-26T10:44:05Z

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From: Richard Weinberger <richard@nod.at>

[ Upstream commit 34653fd8c46e771585fce5975e4243f8fd401914 ]

This commit got merged along with commit 781932375ffc
("ubi: fastmap: Correctly handle interrupted erasures in EBA") upstream but
only the latter has been applied to stable v4.14.54 as commit a23cf10d9abb.
This resulted in a performance regression. Startup on i.MX platforms is
delayed for up to a few seconds depending on the platform.
This fixes ubi fastmap to be of the same performance as it has been before
said fastmap changes.

Fixes: a23cf10d9abb ("ubi: fastmap: Correctly handle interrupted erasures in EBA")
Signed-off-by: Richard Weinberger <richard@nod.at>
Signed-off-by: Martin Kepplinger <martin.kepplinger@ginzinger.com>
---

Richard, although this fixes a major slowdown regression in -stable, do you
consider this "stable" too?

This applies and is tested only for the 4.14 stable tree. It seems to be
equally relevant for 4.9 and 4.4 though.

thanks
martin

drivers/mtd/ubi/build.c | 1 +
drivers/mtd/ubi/eba.c | 4 ++++
drivers/mtd/ubi/fastmap.c | 20 ++++++++++++++++++++
drivers/mtd/ubi/ubi.h | 11 +++++++++++
drivers/mtd/ubi/vmt.c | 1 +
drivers/mtd/ubi/vtbl.c | 16 +++++++++++++++-
6 files changed, 52 insertions(+), 1 deletion(-)

diff --git a/drivers/mtd/ubi/build.c b/drivers/mtd/ubi/build.c
index 18a72da759a0..6445c693d935 100644
--- a/drivers/mtd/ubi/build.c
+++ b/drivers/mtd/ubi/build.c
@@ -526,6 +526,7 @@ void ubi_free_internal_volumes(struct ubi_device *ubi)
for (i = ubi->vtbl_slots;
i < ubi->vtbl_slots + UBI_INT_VOL_COUNT; i++) {
ubi_eba_replace_table(ubi->volumes[i], NULL);
+ ubi_fastmap_destroy_checkmap(ubi->volumes[i]);
kfree(ubi->volumes[i]);
}
}
diff --git a/drivers/mtd/ubi/eba.c b/drivers/mtd/ubi/eba.c
index d0884bd9d955..c4d4b8f07630 100644
--- a/drivers/mtd/ubi/eba.c
+++ b/drivers/mtd/ubi/eba.c
@@ -517,6 +517,9 @@ static int check_mapping(struct ubi_device *ubi, struct ubi_volume *vol, int lnu
if (!ubi->fast_attach)
return 0;

+ if (!vol->checkmap || test_bit(lnum, vol->checkmap))
+ return 0;
+
vidb = ubi_alloc_vid_buf(ubi, GFP_NOFS);
if (!vidb)
return -ENOMEM;
@@ -551,6 +554,7 @@ static int check_mapping(struct ubi_device *ubi, struct ubi_volume *vol, int lnu
goto out_free;
}

+ set_bit(lnum, vol->checkmap);
err = 0;

out_free:
diff --git a/drivers/mtd/ubi/fastmap.c b/drivers/mtd/ubi/fastmap.c
index 5a832bc79b1b..63e8527f7b65 100644
--- a/drivers/mtd/ubi/fastmap.c
+++ b/drivers/mtd/ubi/fastmap.c
@@ -1101,6 +1101,26 @@ int ubi_scan_fastmap(struct ubi_device *ubi, struct ubi_attach_info *ai,
goto out;
}

+int ubi_fastmap_init_checkmap(struct ubi_volume *vol, int leb_count)
+{
+ struct ubi_device *ubi = vol->ubi;
+
+ if (!ubi->fast_attach)
+ return 0;
+
+ vol->checkmap = kcalloc(BITS_TO_LONGS(leb_count), sizeof(unsigned long),
+ GFP_KERNEL);
+ if (!vol->checkmap)
+ return -ENOMEM;
+
+ return 0;
+}
+
+void ubi_fastmap_destroy_checkmap(struct ubi_volume *vol)
+{
+ kfree(vol->checkmap);
+}
+
/**
* ubi_write_fastmap - writes a fastmap.
* @ubi: UBI device object
diff --git a/drivers/mtd/ubi/ubi.h b/drivers/mtd/ubi/ubi.h
index 5fe62653995e..f5ba97c46160 100644
--- a/drivers/mtd/ubi/ubi.h
+++ b/drivers/mtd/ubi/ubi.h
@@ -334,6 +334,9 @@ struct ubi_eba_leb_desc {
* @changing_leb: %1 if the atomic LEB change ioctl command is in progress
* @direct_writes: %1 if direct writes are enabled for this volume
*
+ * @checkmap: bitmap to remember which PEB->LEB mappings got checked,
+ * protected by UBI LEB lock tree.
+ *
* The @corrupted field indicates that the volume's contents is corrupted.
* Since UBI protects only static volumes, this field is not relevant to
* dynamic volumes - it is user's responsibility to assure their data
@@ -377,6 +380,10 @@ struct ubi_volume {
unsigned int updating:1;
unsigned int changing_leb:1;
unsigned int direct_writes:1;
+
+#ifdef CONFIG_MTD_UBI_FASTMAP
+ unsigned long *checkmap;
+#endif
};

/**
@@ -965,8 +972,12 @@ size_t ubi_calc_fm_size(struct ubi_device *ubi);
int ubi_update_fastmap(struct ubi_device *ubi);
int ubi_scan_fastmap(struct ubi_device *ubi, struct ubi_attach_info *ai,
struct ubi_attach_info *scan_ai);
+int ubi_fastmap_init_checkmap(struct ubi_volume *vol, int leb_count);
+void ubi_fastmap_destroy_checkmap(struct ubi_volume *vol);
#else
static inline int ubi_update_fastmap(struct ubi_device *ubi) { return 0; }
+int static inline ubi_fastmap_init_checkmap(struct ubi_volume *vol, int leb_count) { return 0; }
+static inline void ubi_fastmap_destroy_checkmap(struct ubi_volume *vol) {}
#endif

/* block.c */
diff --git a/drivers/mtd/ubi/vmt.c b/drivers/mtd/ubi/vmt.c
index 3fd8d7ff7a02..0be516780e92 100644
--- a/drivers/mtd/ubi/vmt.c
+++ b/drivers/mtd/ubi/vmt.c
@@ -139,6 +139,7 @@ static void vol_release(struct device *dev)
struct ubi_volume *vol = container_of(dev, struct ubi_volume, dev);

ubi_eba_replace_table(vol, NULL);
+ ubi_fastmap_destroy_checkmap(vol);
kfree(vol);
}

diff --git a/drivers/mtd/ubi/vtbl.c b/drivers/mtd/ubi/vtbl.c
index 263743e7b741..94d7a865b135 100644
--- a/drivers/mtd/ubi/vtbl.c
+++ b/drivers/mtd/ubi/vtbl.c
@@ -534,7 +534,7 @@ static int init_volumes(struct ubi_device *ubi,
const struct ubi_attach_info *ai,
const struct ubi_vtbl_record *vtbl)
{
- int i, reserved_pebs = 0;
+ int i, err, reserved_pebs = 0;
struct ubi_ainf_volume *av;
struct ubi_volume *vol;

@@ -620,6 +620,16 @@ static int init_volumes(struct ubi_device *ubi,
(long long)(vol->used_ebs - 1) * vol->usable_leb_size;
vol->used_bytes += av->last_data_size;
vol->last_eb_bytes = av->last_data_size;
+
+ /*
+ * We use ubi->peb_count and not vol->reserved_pebs because
+ * we want to keep the code simple. Otherwise we'd have to
+ * resize/check the bitmap upon volume resize too.
+ * Allocating a few bytes more does not hurt.
+ */
+ err = ubi_fastmap_init_checkmap(vol, ubi->peb_count);
+ if (err)
+ return err;
}

/* And add the layout volume */
@@ -645,6 +655,9 @@ static int init_volumes(struct ubi_device *ubi,
reserved_pebs += vol->reserved_pebs;
ubi->vol_count += 1;
vol->ubi = ubi;
+ err = ubi_fastmap_init_checkmap(vol, UBI_LAYOUT_VOLUME_EBS);
+ if (err)
+ return err;

if (reserved_pebs > ubi->avail_pebs) {
ubi_err(ubi, "not enough PEBs, required %d, available %d",
@@ -849,6 +862,7 @@ int ubi_read_volume_table(struct ubi_device *ubi, struct ubi_attach_info *ai)
out_free:
vfree(ubi->vtbl);
for (i = 0; i < ubi->vtbl_slots + UBI_INT_VOL_COUNT; i++) {
+ ubi_fastmap_destroy_checkmap(ubi->volumes[i]);
kfree(ubi->volumes[i]);
ubi->volumes[i] = NULL;
}
--
2.19.1

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