On Mon, 7 Jul 2025 at 19:53, Zhang Yi <yi.zhang@xxxxxxxxxxxxxxx> wrote: > > From: Zhang Yi <yi.zhang@xxxxxxxxxx> > > Changes since v3: > - Fix the end_pos assignment in patch 01. > - Rename mpage_submit_buffers() to mpage_submit_partial_folio(), and > fix a left shift out-of-bounds problem in patch 03. > - Fix the spelling errors in patch 04. > - Add a comment for NULL 'handle' test in > ext4_journal_ensure_extent_credits(). > - Add patch 11 to limit the maximum order of the folio to 2048 fs > blocks, prevent the overestimation of reserve journal credits during > folios write-back. > Changes since v2: > - Convert the processing of folios writeback in bytes instead of pages. > - Refactor ext4_page_mkwrite() and ensure journal credits in > ext4_block_write_begin() instead of in _ext4_get_block(). > - Enhance tracepoints in ext4_do_writepages(). > - Replace the outdated ext4_da_writepages_trans_blocks() and > ext4_writepage_trans_blocks() with the new helper used to reserve > credits for a single extent. > Changes since v1: > - Make the write-back process supports writing a partial folio if it > exits the mapping loop prematurely due to insufficient sapce or > journal credits, it also fix the potential stale data and > inconsistency issues. > - Fix the same issue regarding the allocation of blocks in > ext4_write_begin() and ext4_page_mkwrite() when delalloc is not > enabled. > > v3: https://lore.kernel.org/linux-ext4/20250701130635.4079595-1-yi.zhang@xxxxxxxxxxxxxxx/ > v2: https://lore.kernel.org/linux-ext4/20250611111625.1668035-1-yi.zhang@xxxxxxxxxxxxxxx/ > v1: https://lore.kernel.org/linux-ext4/20250530062858.458039-1-yi.zhang@xxxxxxxxxxxxxxx/ > > Original Description > > This series addresses the issue that Jan pointed out regarding large > folios support for ext4[1]. The problem is that the credits calculation > may insufficient in ext4_meta_trans_blocks() when allocating blocks > during write back a sufficiently large and discontinuous folio, it > doesn't involve the credits for updating bitmap and group descriptor > block. However, if we fix this issue, it may lead to significant > overestimation on the some filesystems with a lot of block groups. > > The solution involves first ensure that the current journal transaction > has enough credits when we mapping an extent during allocating blocks. > Then if the credits reach the upper limit, exit the current mapping > loop, submit the partial folio and restart a new transaction. Finally, > fix the wrong credits calculation in ext4_meta_trans_blocks(). Please > see the following patches for details. I have applied this patch set on top of the Linux next tree and performed testing. The previously reported regressions [a] are no longer observed. Thank you for providing the fix. Tested-by: Linux Kernel Functional Testing <lkft@xxxxxxxxxx> Reference link: [a] https://lore.kernel.org/all/CA+G9fYsyYQ3ZL4xaSg1-Tt5Evto7Zd+hgNWZEa9cQLbahA1+xg@xxxxxxxxxxxxxx/ > > [1] https://lore.kernel.org/linux-ext4/ht54j6bvjmiqt62xmcveqlo7bmrunqs4ji7wikfteftdjijzek@7tz5gpejaoen/ > > Thanks, > Yi. > > Zhang Yi (11): > ext4: process folios writeback in bytes > ext4: move the calculation of wbc->nr_to_write to mpage_folio_done() > ext4: fix stale data if it bail out of the extents mapping loop > ext4: refactor the block allocation process of ext4_page_mkwrite() > ext4: restart handle if credits are insufficient during allocating > blocks > ext4: enhance tracepoints during the folios writeback > ext4: correct the reserved credits for extent conversion > ext4: reserved credits for one extent during the folio writeback > ext4: replace ext4_writepage_trans_blocks() > ext4: fix insufficient credits calculation in ext4_meta_trans_blocks() > ext4: limit the maximum folio order > > fs/ext4/ext4.h | 4 +- > fs/ext4/extents.c | 6 +- > fs/ext4/ialloc.c | 3 +- > fs/ext4/inline.c | 6 +- > fs/ext4/inode.c | 349 +++++++++++++++++++++++------------- > fs/ext4/move_extent.c | 3 +- > fs/ext4/xattr.c | 2 +- > include/trace/events/ext4.h | 47 ++++- > 8 files changed, 272 insertions(+), 148 deletions(-) > > -- > 2.46.1 -- Linaro LKFT https://lkft.linaro.org
