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ext4: pipeline buffer reads in mext_page_mkuptodate() 

[ Upstream commit 368a83cebbb949adbcc20877c35367178497d9cc ]

Instead of synchronously reading one buffer at a time, submit reads
as we walk the buffers in the first loop, then wait for them in the
second loop.  This should be significantly more efficient, particularly
on HDDs, but I have not measured.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Link: https://patch.msgid.link/20240718223005.568869-2-willy@infradead.org
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Stable-dep-of: 2f3d93e210b9 ("ext4: fix race in buffer_head read fault injection")
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Matthew Wilcox (Oracle) 2024-07-18 23:30:00 +01:00 committed by Greg Kroah-Hartman
parent fbd359a2ee
commit 2266fe580a
1 changed files with 15 additions and 8 deletions
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23
fs/ext4/move_extent.c
View File

@ -173,7 +173,9 @@ mext_page_mkuptodate(struct folio *folio, unsigned from, unsigned to)
sector_t block;
struct buffer_head *bh, *head, *arr[MAX_BUF_PER_PAGE];
unsigned int blocksize, block_start, block_end;
int i, err, nr = 0, partial = 0;
int i, nr = 0;
bool partial = false;
BUG_ON(!folio_test_locked(folio));
BUG_ON(folio_test_writeback(folio));
@ -193,13 +195,13 @@ mext_page_mkuptodate(struct folio *folio, unsigned from, unsigned to)
block_end = block_start + blocksize;
if (block_end <= from || block_start >= to) {
if (!buffer_uptodate(bh))
partial = 1;
partial = true;
continue;
}
if (buffer_uptodate(bh))
continue;
if (!buffer_mapped(bh)) {
err = ext4_get_block(inode, block, bh, 0);
int err = ext4_get_block(inode, block, bh, 0);
if (err)
return err;
if (!buffer_mapped(bh)) {
@ -208,6 +210,12 @@ mext_page_mkuptodate(struct folio *folio, unsigned from, unsigned to)
continue;
}
}
lock_buffer(bh);
if (buffer_uptodate(bh)) {
unlock_buffer(bh);
continue;
}
ext4_read_bh_nowait(bh, 0, NULL);
BUG_ON(nr >= MAX_BUF_PER_PAGE);
arr[nr++] = bh;
}
@ -217,11 +225,10 @@ mext_page_mkuptodate(struct folio *folio, unsigned from, unsigned to)
for (i = 0; i < nr; i++) {
bh = arr[i];
if (!bh_uptodate_or_lock(bh)) {
err = ext4_read_bh(bh, 0, NULL);
if (err)
return err;
}
wait_on_buffer(bh);
if (buffer_uptodate(bh))
continue;
return -EIO;
}
out:
if (!partial)