diff options
| author | Christoph Hellwig <hch@lst.de> | 2025-10-17 05:45:48 +0200 |
|---|---|---|
| committer | Christian Brauner <brauner@kernel.org> | 2025-10-29 15:54:31 +0100 |
| commit | 90db4d4441f58d433ecf74f7e3bd17e0a553c20c (patch) | |
| tree | 8e436c715c54452cb72e8daee40fdef8887ad46a | |
| parent | 151d0922bf638a4e4235758d04b31f48bfcbb798 (diff) | |
writeback: allow the file system to override MIN_WRITEBACK_PAGES
The relatively low minimal writeback size of 4MiB means that written back
inodes on rotational media are switched a lot. Besides introducing
additional seeks, this also can lead to extreme file fragmentation on
zoned devices when a lot of files are cached relative to the available
writeback bandwidth.
Add a superblock field that allows the file system to override the
default size.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://patch.msgid.link/20251017034611.651385-3-hch@lst.de
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
| -rw-r--r-- | fs/fs-writeback.c | 14 | ||||
| -rw-r--r-- | fs/super.c | 1 | ||||
| -rw-r--r-- | include/linux/fs.h | 1 | ||||
| -rw-r--r-- | include/linux/writeback.h | 5 |
4 files changed, 12 insertions, 9 deletions
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c index 30de37865fa1..52763fa499d6 100644 --- a/fs/fs-writeback.c +++ b/fs/fs-writeback.c @@ -33,11 +33,6 @@ #include "internal.h" /* - * 4MB minimal write chunk size - */ -#define MIN_WRITEBACK_PAGES (4096UL >> (PAGE_SHIFT - 10)) - -/* * Passed into wb_writeback(), essentially a subset of writeback_control */ struct wb_writeback_work { @@ -1889,8 +1884,8 @@ out: return ret; } -static long writeback_chunk_size(struct bdi_writeback *wb, - struct wb_writeback_work *work) +static long writeback_chunk_size(struct super_block *sb, + struct bdi_writeback *wb, struct wb_writeback_work *work) { long pages; @@ -1913,7 +1908,8 @@ static long writeback_chunk_size(struct bdi_writeback *wb, pages = min(wb->avg_write_bandwidth / 2, global_wb_domain.dirty_limit / DIRTY_SCOPE); pages = min(pages, work->nr_pages); - return round_down(pages + MIN_WRITEBACK_PAGES, MIN_WRITEBACK_PAGES); + return round_down(pages + sb->s_min_writeback_pages, + sb->s_min_writeback_pages); } /* @@ -2015,7 +2011,7 @@ static long writeback_sb_inodes(struct super_block *sb, inode->i_state |= I_SYNC; wbc_attach_and_unlock_inode(&wbc, inode); - write_chunk = writeback_chunk_size(wb, work); + write_chunk = writeback_chunk_size(inode->i_sb, wb, work); wbc.nr_to_write = write_chunk; wbc.pages_skipped = 0; diff --git a/fs/super.c b/fs/super.c index 5bab94fb7e03..599c1d2641fe 100644 --- a/fs/super.c +++ b/fs/super.c @@ -389,6 +389,7 @@ static struct super_block *alloc_super(struct file_system_type *type, int flags, goto fail; if (list_lru_init_memcg(&s->s_inode_lru, s->s_shrink)) goto fail; + s->s_min_writeback_pages = MIN_WRITEBACK_PAGES; return s; fail: diff --git a/include/linux/fs.h b/include/linux/fs.h index a5dbfa20f8d7..6bf369095d2e 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -1583,6 +1583,7 @@ struct super_block { spinlock_t s_inode_wblist_lock; struct list_head s_inodes_wb; /* writeback inodes */ + long s_min_writeback_pages; } __randomize_layout; static inline struct user_namespace *i_user_ns(const struct inode *inode) diff --git a/include/linux/writeback.h b/include/linux/writeback.h index 22dd4adc5667..49e1dd96f43e 100644 --- a/include/linux/writeback.h +++ b/include/linux/writeback.h @@ -374,4 +374,9 @@ bool redirty_page_for_writepage(struct writeback_control *, struct page *); void sb_mark_inode_writeback(struct inode *inode); void sb_clear_inode_writeback(struct inode *inode); +/* + * 4MB minimal write chunk size + */ +#define MIN_WRITEBACK_PAGES (4096UL >> (PAGE_SHIFT - 10)) + #endif /* WRITEBACK_H */ |