[PATCH 4/6] EXT4: remove congestion_wait from ext4_bio_write_page, and simplify
From: NeilBrown <hidden>
Date: 2021-09-17 03:00:02
Also in:
linux-doc, linux-ext4, linux-fsdevel, linux-mm, linux-xfs, lkml
Subsystem:
ext4 file system, filesystems (vfs and infrastructure), the rest · Maintainers:
"Theodore Ts'o", Alexander Viro, Christian Brauner, Linus Torvalds
congestion_wait() is indistinguishable from schedule_timeout_uninterruptible(). It is best avoided and should be deprecated. It is not needed in ext4_bio_write_page(). There are two cases. If there are no ->io_bio yet, then it is appropriate to use __GFP_NOFAIL which does the waiting in a better place. The code already uses this flag on the second attempt. This patch changes to it always use that flag for this case. If there *are* ->io_bio (in which case the allocation was non-blocking) we submit the io and return the first case. No waiting is needed in this case. So remove the congestion_wait() call, and simplify the code so that the two cases are somewhat clearer. Remove the "if (io->io_bio)" before calling ext4_io_submit() as that test is performed internally by that function. Signed-off-by: NeilBrown <redacted> --- fs/ext4/page-io.c | 13 +++++-------- 1 file changed, 5 insertions(+), 8 deletions(-)
diff --git a/fs/ext4/page-io.c b/fs/ext4/page-io.c
index f038d578d8d8..3b6ece0d3ad6 100644
--- a/fs/ext4/page-io.c
+++ b/fs/ext4/page-io.c@@ -506,7 +506,7 @@ int ext4_bio_write_page(struct ext4_io_submit *io, * can't happen in the common case of blocksize == PAGE_SIZE. */ if (fscrypt_inode_uses_fs_layer_crypto(inode) && nr_to_submit) { - gfp_t gfp_flags = GFP_NOFS; + gfp_t gfp_flags; unsigned int enc_bytes = round_up(len, i_blocksize(inode)); /*
@@ -514,21 +514,18 @@ int ext4_bio_write_page(struct ext4_io_submit *io, * a waiting mask (i.e. request guaranteed allocation) on the * first page of the bio. Otherwise it can deadlock. */ + retry_encrypt: if (io->io_bio) gfp_flags = GFP_NOWAIT | __GFP_NOWARN; - retry_encrypt: + else + gfp_flags = GFP_NOFS | __GFP_NOFAIL; bounce_page = fscrypt_encrypt_pagecache_blocks(page, enc_bytes, 0, gfp_flags); if (IS_ERR(bounce_page)) { ret = PTR_ERR(bounce_page); if (ret == -ENOMEM && (io->io_bio || wbc->sync_mode == WB_SYNC_ALL)) { - gfp_flags = GFP_NOFS; - if (io->io_bio) - ext4_io_submit(io); - else - gfp_flags |= __GFP_NOFAIL; - congestion_wait(BLK_RW_ASYNC, HZ/50); + ext4_io_submit(io); goto retry_encrypt; }