Discussion:
[PATCH 4/9] btrfs: Avoid a rescan for a device which was already not found.
Goffredo Baroncelli
2018-06-04 19:26:06 UTC
Permalink
Resend this patch because I am not sure that all received it.
BR
G.Baroncelli


-------- Forwarded Message --------
Subject: [PATCH 4/9] btrfs: Avoid a rescan for a device which was already not found.
Date: Sun, 3 Jun 2018 20:53:43 +0200
From: Goffredo Baroncelli <***@gmail.com>
To: grub-***@gnu.org
CC: Goffredo Baroncelli <***@inwind.it>

If a device is not found, record this failure by storing NULL in
data->devices_attached[]. This way we avoid unnecessary devices rescan,
and speedup the reads in case of a degraded array.

Signed-off-by: Goffredo Baroncelli <***@inwind.it>
---
grub-core/fs/btrfs.c | 19 +++++++++----------
1 file changed, 9 insertions(+), 10 deletions(-)

diff --git a/grub-core/fs/btrfs.c b/grub-core/fs/btrfs.c
index 9b3a22772..b64b692f8 100644
--- a/grub-core/fs/btrfs.c
+++ b/grub-core/fs/btrfs.c
@@ -588,7 +588,7 @@ find_device_iter (const char *name, void *data)
}

static grub_device_t
-find_device (struct grub_btrfs_data *data, grub_uint64_t id, int do_rescan)
+find_device (struct grub_btrfs_data *data, grub_uint64_t id)
{
struct find_device_ctx ctx = {
.data = data,
@@ -600,12 +600,9 @@ find_device (struct grub_btrfs_data *data, grub_uint64_t id, int do_rescan)
for (i = 0; i < data->n_devices_attached; i++)
if (id == data->devices_attached[i].id)
return data->devices_attached[i].dev;
- if (do_rescan)
- grub_device_iterate (find_device_iter, &ctx);
- if (!ctx.dev_found)
- {
- return NULL;
- }
+
+ grub_device_iterate (find_device_iter, &ctx);
+
data->n_devices_attached++;
if (data->n_devices_attached > data->n_devices_allocated)
{
@@ -617,7 +614,8 @@ find_device (struct grub_btrfs_data *data, grub_uint64_t id, int do_rescan)
* sizeof (data->devices_attached[0]));
if (!data->devices_attached)
{
- grub_device_close (ctx.dev_found);
+ if (ctx.dev_found)
+ grub_device_close (ctx.dev_found);
data->devices_attached = tmp;
return NULL;
}
@@ -896,7 +894,7 @@ grub_btrfs_read_logical (struct grub_btrfs_data *data, grub_disk_addr_t addr,
" for laddr 0x%" PRIxGRUB_UINT64_T "\n", paddr,
addr);

- dev = find_device (data, stripe->device_id, j);
+ dev = find_device (data, stripe->device_id);
if (!dev)
{
grub_dprintf ("btrfs",
@@ -973,7 +971,8 @@ grub_btrfs_unmount (struct grub_btrfs_data *data)
unsigned i;
/* The device 0 is closed one layer upper. */
for (i = 1; i < data->n_devices_attached; i++)
- grub_device_close (data->devices_attached[i].dev);
+ if (data->devices_attached[i].dev)
+ grub_device_close (data->devices_attached[i].dev);
grub_free (data->devices_attached);
grub_free (data->extent);
grub_free (data);
--
2.17.1
Daniel Kiper
2018-06-14 11:45:09 UTC
Permalink
Post by Goffredo Baroncelli
Resend this patch because I am not sure that all received it.
It looks that #4 is a bit unfortunate for you and/or patch series... :-)))
Post by Goffredo Baroncelli
BR
G.Baroncelli
-------- Forwarded Message --------
Subject: [PATCH 4/9] btrfs: Avoid a rescan for a device which was already not found.
Date: Sun, 3 Jun 2018 20:53:43 +0200
If a device is not found, record this failure by storing NULL in
data->devices_attached[]. This way we avoid unnecessary devices rescan,
Hmmm... Could you point me out where this store happens below?

Daniel
Post by Goffredo Baroncelli
and speedup the reads in case of a degraded array.
---
grub-core/fs/btrfs.c | 19 +++++++++----------
1 file changed, 9 insertions(+), 10 deletions(-)
diff --git a/grub-core/fs/btrfs.c b/grub-core/fs/btrfs.c
index 9b3a22772..b64b692f8 100644
--- a/grub-core/fs/btrfs.c
+++ b/grub-core/fs/btrfs.c
@@ -588,7 +588,7 @@ find_device_iter (const char *name, void *data)
}
static grub_device_t
-find_device (struct grub_btrfs_data *data, grub_uint64_t id, int do_rescan)
+find_device (struct grub_btrfs_data *data, grub_uint64_t id)
{
struct find_device_ctx ctx = {
.data = data,
@@ -600,12 +600,9 @@ find_device (struct grub_btrfs_data *data, grub_uint64_t id, int do_rescan)
for (i = 0; i < data->n_devices_attached; i++)
if (id == data->devices_attached[i].id)
return data->devices_attached[i].dev;
- if (do_rescan)
- grub_device_iterate (find_device_iter, &ctx);
- if (!ctx.dev_found)
- {
- return NULL;
- }
+
+ grub_device_iterate (find_device_iter, &ctx);
+
data->n_devices_attached++;
if (data->n_devices_attached > data->n_devices_allocated)
{
@@ -617,7 +614,8 @@ find_device (struct grub_btrfs_data *data, grub_uint64_t id, int do_rescan)
* sizeof (data->devices_attached[0]));
if (!data->devices_attached)
{
- grub_device_close (ctx.dev_found);
+ if (ctx.dev_found)
+ grub_device_close (ctx.dev_found);
data->devices_attached = tmp;
return NULL;
}
@@ -896,7 +894,7 @@ grub_btrfs_read_logical (struct grub_btrfs_data *data, grub_disk_addr_t addr,
" for laddr 0x%" PRIxGRUB_UINT64_T "\n", paddr,
addr);
- dev = find_device (data, stripe->device_id, j);
+ dev = find_device (data, stripe->device_id);
if (!dev)
{
grub_dprintf ("btrfs",
@@ -973,7 +971,8 @@ grub_btrfs_unmount (struct grub_btrfs_data *data)
unsigned i;
/* The device 0 is closed one layer upper. */
for (i = 1; i < data->n_devices_attached; i++)
- grub_device_close (data->devices_attached[i].dev);
+ if (data->devices_attached[i].dev)
+ grub_device_close (data->devices_attached[i].dev);
grub_free (data->devices_attached);
grub_free (data->extent);
grub_free (data);
--
2.17.1
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https://lists.gnu.org/mailman/listinfo/grub-devel
Goffredo Baroncelli
2018-06-14 18:06:10 UTC
Permalink
Post by Daniel Kiper
Post by Goffredo Baroncelli
Resend this patch because I am not sure that all received it.
It looks that #4 is a bit unfortunate for you and/or patch series... :-)))
Yes, but I have another suspect: the patch #4 never changed, and I know that gmail "collapse" the emails when these are equal...
Post by Daniel Kiper
Post by Goffredo Baroncelli
BR
G.Baroncelli
-------- Forwarded Message --------
Subject: [PATCH 4/9] btrfs: Avoid a rescan for a device which was already not found.
Date: Sun, 3 Jun 2018 20:53:43 +0200
If a device is not found, record this failure by storing NULL in
data->devices_attached[]. This way we avoid unnecessary devices rescan,
Hmmm... Could you point me out where this store happens below?
Se below
[...]
Post by Daniel Kiper
Post by Goffredo Baroncelli
for (i = 0; i < data->n_devices_attached; i++)
if (id == data->devices_attached[i].id)
return data->devices_attached[i].dev;
- if (do_rescan)
- grub_device_iterate (find_device_iter, &ctx);
- if (!ctx.dev_found)
- {
- return NULL;
- }
The check above, performs a function exit if ctx.dev_found is NULL. Removing this check allows to store the NULL in the array.
In case of another iteration we know that the device is missing without doing a rescam
Post by Daniel Kiper
Post by Goffredo Baroncelli
+
+ grub_device_iterate (find_device_iter, &ctx);
+
data->n_devices_attached++;
if (data->n_devices_attached > data->n_devices_allocated)
{
@@ -617,7 +614,8 @@ find_device (struct grub_btrfs_data *data, grub_uint64_t id, int do_rescan)
* sizeof (data->devices_attached[0]));
if (!data->devices_attached)
{
- grub_device_close (ctx.dev_found);
+ if (ctx.dev_found)
+ grub_device_close (ctx.dev_found);
data->devices_attached = tmp;
return NULL;
}
@@ -896,7 +894,7 @@ grub_btrfs_read_logical (struct grub_btrfs_data *data, grub_disk_addr_t addr,
" for laddr 0x%" PRIxGRUB_UINT64_T "\n", paddr,
addr);
- dev = find_device (data, stripe->device_id, j);
+ dev = find_device (data, stripe->device_id);
if (!dev)
{
grub_dprintf ("btrfs",
@@ -973,7 +971,8 @@ grub_btrfs_unmount (struct grub_btrfs_data *data)
unsigned i;
/* The device 0 is closed one layer upper. */
for (i = 1; i < data->n_devices_attached; i++)
- grub_device_close (data->devices_attached[i].dev);
+ if (data->devices_attached[i].dev)
+ grub_device_close (data->devices_attached[i].dev);
grub_free (data->devices_attached);
grub_free (data->extent);
grub_free (data);
--
2.17.1
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Key fingerprint BBF5 1610 0B64 DAC6 5F7D 17B2 0EDA 9B37 8B82 E0B5
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