diff options
| author | Christoph Hellwig <hch@lst.de> | 2025-04-24 10:25:21 +0200 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2025-04-24 07:32:17 -0600 |
| commit | 7b720c720253e2070459420b2628a7b9ee6733b3 (patch) | |
| tree | 87a2118c4c801a4cc9dc988864afd190e0e0b55e /block | |
| parent | 1d019736b6f812bebf3ef89d6e887d06e2a822fc (diff) | |
block: never reduce ra_pages in blk_apply_bdi_limits
When the user increased the read-ahead size through sysfs this value
currently get lost if the device is reprobe, including on a resume
from suspend.
As there is no hardware limitation for the read-ahead size there is
no real need to reset it or track a separate hardware limitation
like for max_sectors.
This restores the pre-atomic queue limit behavior in the sd driver as
sd did not use blk_queue_io_opt and thus never updated the read ahead
size to the value based of the optimal I/O, but changes behavior for
all other drivers. As the new behavior seems useful and sd is the
driver for which the readahead size tweaks are most useful that seems
like a worthwhile trade off.
Fixes: 804e498e0496 ("sd: convert to the atomic queue limits API")
Reported-by: Holger Hoffstätte <holger@applied-asynchrony.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Tested-by: Holger Hoffstätte <holger@applied-asynchrony.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Link: https://lore.kernel.org/r/20250424082521.1967286-1-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block')
| -rw-r--r-- | block/blk-settings.c | 8 |
1 files changed, 7 insertions, 1 deletions
diff --git a/block/blk-settings.c b/block/blk-settings.c index 6b2dbe645d23..4817e7ca03f8 100644 --- a/block/blk-settings.c +++ b/block/blk-settings.c @@ -61,8 +61,14 @@ void blk_apply_bdi_limits(struct backing_dev_info *bdi, /* * For read-ahead of large files to be effective, we need to read ahead * at least twice the optimal I/O size. + * + * There is no hardware limitation for the read-ahead size and the user + * might have increased the read-ahead size through sysfs, so don't ever + * decrease it. */ - bdi->ra_pages = max(lim->io_opt * 2 / PAGE_SIZE, VM_READAHEAD_PAGES); + bdi->ra_pages = max3(bdi->ra_pages, + lim->io_opt * 2 / PAGE_SIZE, + VM_READAHEAD_PAGES); bdi->io_pages = lim->max_sectors >> PAGE_SECTORS_SHIFT; } |