From: Trond Myklebust Add a helper to allow filesystems to attempt to free the 'dropbehind' folio. Signed-off-by: Trond Myklebust Link: https://lore.kernel.org/all/5588a06f6d5a2cf6746828e2d36e7ada668b1739.1745381692.git.trond.myklebust@hammerspace.com/ Reviewed-by: Mike Snitzer --- include/linux/pagemap.h | 1 + mm/filemap.c | 5 +++-- 2 files changed, 4 insertions(+), 2 deletions(-) diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h index 12a12dae727d..201b7c6f6441 100644 --- a/include/linux/pagemap.h +++ b/include/linux/pagemap.h @@ -1221,6 +1221,7 @@ void folio_wait_writeback(struct folio *folio); int folio_wait_writeback_killable(struct folio *folio); void end_page_writeback(struct page *page); void folio_end_writeback(struct folio *folio); +void folio_end_dropbehind(struct folio *folio); void folio_wait_stable(struct folio *folio); void __folio_mark_dirty(struct folio *folio, struct address_space *, int warn); void folio_account_cleaned(struct folio *folio, struct bdi_writeback *wb); diff --git a/mm/filemap.c b/mm/filemap.c index 751838ef05e5..66cec689bec4 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -1608,7 +1608,7 @@ static void filemap_end_dropbehind(struct folio *folio) * completes. Do that now. If we fail, it's likely because of a big folio - * just reset dropbehind for that case and latter completions should invalidate. */ -static void filemap_end_dropbehind_write(struct folio *folio) +void folio_end_dropbehind(struct folio *folio) { if (!folio_test_dropbehind(folio)) return; @@ -1625,6 +1625,7 @@ static void filemap_end_dropbehind_write(struct folio *folio) folio_unlock(folio); } } +EXPORT_SYMBOL_GPL(folio_end_dropbehind); /** * folio_end_writeback - End writeback against a folio. @@ -1660,7 +1661,7 @@ void folio_end_writeback(struct folio *folio) if (__folio_end_writeback(folio)) folio_wake_bit(folio, PG_writeback); - filemap_end_dropbehind_write(folio); + folio_end_dropbehind(folio); acct_reclaim_writeback(folio); folio_put(folio); } -- 2.51.0 From: Trond Myklebust Filesystems such as NFS may need to defer dropbehind until after their 2-stage writes are done. This adds a helper folio_end_writeback_no_dropbehind() that allows them to release the writeback flag without immediately dropping the folio. Signed-off-by: Trond Myklebust --- include/linux/pagemap.h | 1 + mm/filemap.c | 29 +++++++++++++++++++++++------ 2 files changed, 24 insertions(+), 6 deletions(-) diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h index 201b7c6f6441..5b26465358ce 100644 --- a/include/linux/pagemap.h +++ b/include/linux/pagemap.h @@ -1221,6 +1221,7 @@ void folio_wait_writeback(struct folio *folio); int folio_wait_writeback_killable(struct folio *folio); void end_page_writeback(struct page *page); void folio_end_writeback(struct folio *folio); +void folio_end_writeback_no_dropbehind(struct folio *folio); void folio_end_dropbehind(struct folio *folio); void folio_wait_stable(struct folio *folio); void __folio_mark_dirty(struct folio *folio, struct address_space *, int warn); diff --git a/mm/filemap.c b/mm/filemap.c index 66cec689bec4..d12bbb4c9d8a 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -1628,14 +1628,15 @@ void folio_end_dropbehind(struct folio *folio) EXPORT_SYMBOL_GPL(folio_end_dropbehind); /** - * folio_end_writeback - End writeback against a folio. + * folio_end_writeback_no_dropbehind - End writeback against a folio. * @folio: The folio. * * The folio must actually be under writeback. + * This call is intended for filesystems that need to defer dropbehind. * * Context: May be called from process or interrupt context. */ -void folio_end_writeback(struct folio *folio) +void folio_end_writeback_no_dropbehind(struct folio *folio) { VM_BUG_ON_FOLIO(!folio_test_writeback(folio), folio); @@ -1651,6 +1652,25 @@ void folio_end_writeback(struct folio *folio) folio_rotate_reclaimable(folio); } + if (__folio_end_writeback(folio)) + folio_wake_bit(folio, PG_writeback); + + acct_reclaim_writeback(folio); +} +EXPORT_SYMBOL_GPL(folio_end_writeback_no_dropbehind); + +/** + * folio_end_writeback - End writeback against a folio. + * @folio: The folio. + * + * The folio must actually be under writeback. + * + * Context: May be called from process or interrupt context. + */ +void folio_end_writeback(struct folio *folio) +{ + VM_BUG_ON_FOLIO(!folio_test_writeback(folio), folio); + /* * Writeback does not hold a folio reference of its own, relying * on truncation to wait for the clearing of PG_writeback. @@ -1658,11 +1678,8 @@ void folio_end_writeback(struct folio *folio) * reused before the folio_wake_bit(). */ folio_get(folio); - if (__folio_end_writeback(folio)) - folio_wake_bit(folio, PG_writeback); - + folio_end_writeback_no_dropbehind(folio); folio_end_dropbehind(folio); - acct_reclaim_writeback(folio); folio_put(folio); } EXPORT_SYMBOL(folio_end_writeback); -- 2.51.0 From: Trond Myklebust The NFS client needs to defer dropbehind until after any writes to the folio have been persisted on the server. Since this may be a 2 step process, use folio_end_writeback_no_dropbehind() to allow release of the writeback flag, and then call folio_end_dropbehind() once the COMMIT is done. Signed-off-by: Trond Myklebust --- fs/nfs/file.c | 9 +++++---- fs/nfs/nfs4file.c | 1 + fs/nfs/write.c | 4 +++- 3 files changed, 9 insertions(+), 5 deletions(-) diff --git a/fs/nfs/file.c b/fs/nfs/file.c index 8059ece82468..9025c93bcaf1 100644 --- a/fs/nfs/file.c +++ b/fs/nfs/file.c @@ -361,6 +361,8 @@ static bool nfs_want_read_modify_write(struct file *file, struct folio *folio, if (pnfs_ld_read_whole_page(file_inode(file))) return true; + if (folio_test_dropbehind(folio)) + return false; /* Open for reading too? */ if (file->f_mode & FMODE_READ) return true; @@ -380,7 +382,6 @@ static int nfs_write_begin(const struct kiocb *iocb, loff_t pos, unsigned len, struct folio **foliop, void **fsdata) { - fgf_t fgp = FGP_WRITEBEGIN; struct folio *folio; struct file *file = iocb->ki_filp; int once_thru = 0; @@ -390,10 +391,8 @@ static int nfs_write_begin(const struct kiocb *iocb, file, mapping->host->i_ino, len, (long long) pos); nfs_truncate_last_folio(mapping, i_size_read(mapping->host), pos); - fgp |= fgf_set_order(len); start: - folio = __filemap_get_folio(mapping, pos >> PAGE_SHIFT, fgp, - mapping_gfp_mask(mapping)); + folio = write_begin_get_folio(iocb, mapping, pos >> PAGE_SHIFT, len); if (IS_ERR(folio)) return PTR_ERR(folio); *foliop = folio; @@ -405,6 +404,7 @@ static int nfs_write_begin(const struct kiocb *iocb, } else if (!once_thru && nfs_want_read_modify_write(file, folio, pos, len)) { once_thru = 1; + folio_clear_dropbehind(folio); ret = nfs_read_folio(file, folio); folio_put(folio); if (!ret) @@ -949,5 +949,6 @@ const struct file_operations nfs_file_operations = { .splice_write = iter_file_splice_write, .check_flags = nfs_check_flags, .setlease = simple_nosetlease, + .fop_flags = FOP_DONTCACHE, }; EXPORT_SYMBOL_GPL(nfs_file_operations); diff --git a/fs/nfs/nfs4file.c b/fs/nfs/nfs4file.c index c9a0d1e420c6..7f43e890d356 100644 --- a/fs/nfs/nfs4file.c +++ b/fs/nfs/nfs4file.c @@ -456,4 +456,5 @@ const struct file_operations nfs4_file_operations = { #else .llseek = nfs_file_llseek, #endif + .fop_flags = FOP_DONTCACHE, }; diff --git a/fs/nfs/write.c b/fs/nfs/write.c index 647c53d1418a..a671de3dda07 100644 --- a/fs/nfs/write.c +++ b/fs/nfs/write.c @@ -296,7 +296,7 @@ static void nfs_folio_end_writeback(struct folio *folio) { struct nfs_server *nfss = NFS_SERVER(folio->mapping->host); - folio_end_writeback(folio); + folio_end_writeback_no_dropbehind(folio); if (atomic_long_dec_return(&nfss->writeback) < NFS_CONGESTION_OFF_THRESH) { nfss->write_congested = 0; @@ -745,6 +745,8 @@ static void nfs_inode_remove_request(struct nfs_page *req) clear_bit(PG_MAPPED, &req->wb_head->wb_flags); } spin_unlock(&mapping->i_private_lock); + + folio_end_dropbehind(folio); } nfs_page_group_unlock(req); -- 2.51.0