6.6-stable review patch. If anyone has any objections, please let me know.
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From: Matthew Wilcox (Oracle) willy@infradead.org
[ 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 --- fs/ext4/move_extent.c | 23 +++++++++++++++-------- 1 file changed, 15 insertions(+), 8 deletions(-)
diff --git a/fs/ext4/move_extent.c b/fs/ext4/move_extent.c index a3aa85795d4a1..28d59548770d7 100644 --- a/fs/ext4/move_extent.c +++ b/fs/ext4/move_extent.c @@ -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)