Comment 26 for bug 1475166

Hi Bryan,

We have done bisection, and found the first bad commit is "34b48db" as shown below.
With this bad commit, the filesystem returns I/O error while copying files to disk.

We use the same config file copy from ubuntu 14.10, and follow the build instruction[1].
Would you like to build an install-able ISO image with reverting this commit? And then we can verify if the installation issue can be solved.

[1] https://wiki.ubuntu.com/KernelTeam/GitKernelBuild#Kernel_Build_and_Installation

commit 34b48db66e08ca1c1bc07cf305d672ac940268dc
Author: Christoph Hellwig <email address hidden>
Date: Sat Sep 6 16:08:05 2014 -0700
    block: remove artifical max_hw_sectors cap
    Set max_sectors to the value the drivers provides as hardware limit by
    default. Linux had proper I/O throttling for a long time and doesn't
    rely on a artifically small maximum I/O size anymore. By not limiting
    the I/O size by default we remove an annoying tuning step required for
    most Linux installation.
    Note that both the user, and if absolutely required the driver can still
    impose a limit for FS requests below max_hw_sectors_kb.
    Signed-off-by: Christoph Hellwig <email address hidden>
    Signed-off-by: Jens Axboe <email address hidden>
diff --git a/block/blk-settings.c b/block/blk-settings.c
index aa02247..6ed2cbe 100644
--- a/block/blk-settings.c
+++ b/block/blk-settings.c
@@ -257,9 +257,7 @@ void blk_limits_max_hw_sectors(struct queue_limits *limits, unsigned int max_hw_
                       __func__, max_hw_sectors);
        }
- limits->max_hw_sectors = max_hw_sectors;
- limits->max_sectors = min_t(unsigned int, max_hw_sectors,
- BLK_DEF_MAX_SECTORS);
+ limits->max_sectors = limits->max_hw_sectors = max_hw_sectors;
 }
 EXPORT_SYMBOL(blk_limits_max_hw_sectors);
diff --git a/drivers/block/aoe/aoeblk.c b/drivers/block/aoe/aoeblk.c
index dd73e1f..46c282f 100644
--- a/drivers/block/aoe/aoeblk.c
+++ b/drivers/block/aoe/aoeblk.c
@@ -395,7 +395,7 @@ aoeblk_gdalloc(void *vp)
        WARN_ON(d->flags & DEVFL_TKILL);
        WARN_ON(d->gd);
        WARN_ON(d->flags & DEVFL_UP);
- blk_queue_max_hw_sectors(q, BLK_DEF_MAX_SECTORS);
+ blk_queue_max_hw_sectors(q, 1024);
        q->backing_dev_info.name = "aoe";
        q->backing_dev_info.ra_pages = READ_AHEAD / PAGE_CACHE_SIZE;
        d->bufpool = mp;
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 0207a78..74d14db 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -1186,7 +1186,6 @@ extern int blk_verify_command(unsigned char *cmd, fmode_t has_write_perm);
 enum blk_default_limits {
        BLK_MAX_SEGMENTS = 128,
        BLK_SAFE_MAX_SECTORS = 255,
- BLK_DEF_MAX_SECTORS = 1024,
        BLK_MAX_SEGMENT_SIZE = 65536,
        BLK_SEG_BOUNDARY_MASK = 0xFFFFFFFFUL,
 };