From 41b8d7ba50ac03a262928d7681bf34259b339180 Mon Sep 17 00:00:00 2001 From: Goffredo Baroncelli Date: Mon, 22 Oct 2018 19:29:34 +0200 Subject: [PATCH] btrfs: Avoid a rescan for a device which was already not found Currently read from missing device triggers rescan. However, it is never recorded that the device is missing. So, each read of a missing device triggers rescan again and again. This behavior causes a lot of unneeded rescans leading to huge slowdowns. This patch fixes above mentioned issue. Information about missing devices is stored in the data->devices_attached[] array as NULL value in dev member. Rescan is triggered only if no information is found for a given device. This means that only first time read triggers rescan. The patch drops premature return. This way data->devices_attached[] is filled even when a given device is missing. Signed-off-by: Goffredo Baroncelli Signed-off-by: Daniel Kiper Reviewed-by: Daniel Kiper --- grub-core/fs/btrfs.c | 17 +++++++++-------- 1 file changed, 9 insertions(+), 8 deletions(-) diff --git a/grub-core/fs/btrfs.c b/grub-core/fs/btrfs.c index 9818385e1..ca0277bee 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, @@ -600,10 +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) { @@ -615,7 +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; } @@ -897,7 +897,7 @@ 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", @@ -974,7 +974,8 @@ 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);