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b=aBgTcmnwJrZ1+/3QcGrLPplzwWBbMG+3sWVbJLN1FsK+6Kd7TvClQcCxFCTylY8zh bfV/FQTodj3YEi+N3PF57piWGirT4j0ZXDbtvQRA80cYog4nLcINqIjq4+8pVQlCEO diWY6pz2yAwitgblNOcfwLJCKnM02+OEkF4tkSSiusXhvzMDGAX+K+LiEMpobifCDa tAga5HiW01jocQrnJg4JeQVKaoFqpO1fukO2xgYHh/Hf+Ubi+MZ792YjRom0ISUGgL XRNkFcXIL5uYrSSuBvlL4gQPCkE0wTsQO2lFHsDOD58f+G8DRIuICTeZpXjS/gcaSO JOIzIy32Es22g== Date: Fri, 21 Nov 2025 18:05:01 +0000 From: Jaegeuk Kim To: Christoph Hellwig Cc: linux-kernel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, Matthew Wilcox , Andrew Morton , linux-fsdevel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH 1/2] f2fs: improve readahead for POSIX_FADV_WILLNEED Message-ID: References: <20251121014202.1969909-1-jaegeuk@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Stat-Signature: qd4ifgrx9bmn5nbxbzbx94eptwqmih5y X-Rspam-User: X-Rspamd-Queue-Id: 45411A000B X-Rspamd-Server: rspam01 X-HE-Tag: 1763748304-430535 X-HE-Meta: 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 QTXmWee+ Ar7BqISe/+7ddmx8Z96hwkNpe2gQfA2s1z+V1MdYKYMg1SbYQyPQfYogQcxHiA8rJQ4UtvWAZuhwW3J9N0aeLdWZChgW1WDGjpmgHWEzVF+AVk9+Nic6b3yV6K7vzJHVFPpSf0W7SZnPkmwfpwNWgj1XSVBnAPVGbqvTfw9EvoeJ8fzE6CMaqlqAbtWR0//FWdHHherLTkcRjey/UYta0jCsIMQY8rfUvePMtIsvZeJPZ7rgxmfVVdDRc0TXngdWHTm1pbfv5R2pSGJ6rgl2UnA/fUqTUK0X3VQ4mraPXQjW761OYtXZLt8XyaZ7x/PznpAA7 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 11/20, Christoph Hellwig wrote: > On Fri, Nov 21, 2025 at 01:42:01AM +0000, Jaegeuk Kim wrote: > > This patch boosts readahead for POSIX_FADV_WILLNEED. > > How? That's not a good changelog. > > Also open coding the read-ahead logic is not a good idea. The only > f2fs-specific bits are the compression check, and the extent precaching, > but you surely should be able to share a read-ahead helper with common > code instead of duplicating the logic. Ok, let me try to write up and post a generic version of the changes. > > > > > Signed-off-by: Jaegeuk Kim > > --- > > fs/f2fs/data.c | 61 ++++++++++++++++++++++++++++++++++++++++++++++++++ > > fs/f2fs/f2fs.h | 1 + > > fs/f2fs/file.c | 9 +++++--- > > 3 files changed, 68 insertions(+), 3 deletions(-) > > > > diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c > > index a0433c8a4d84..d95974d79fb3 100644 > > --- a/fs/f2fs/data.c > > +++ b/fs/f2fs/data.c > > @@ -2710,6 +2710,67 @@ static void f2fs_readahead(struct readahead_control *rac) > > f2fs_mpage_readpages(inode, rac, NULL); > > } > > > > +int f2fs_readahead_pages(struct file *file, loff_t offset, loff_t len) > > +{ > > + struct inode *inode = file_inode(file); > > + struct address_space *mapping = file->f_mapping; > > + pgoff_t start_index = offset >> PAGE_SHIFT; > > + loff_t endbyte = offset + len; > > + pgoff_t end_index; > > + unsigned long nrpages; > > + unsigned long ra_pages = (16 * 1024 * 1024) / PAGE_SIZE; > > + DEFINE_READAHEAD(ractl, NULL, &file->f_ra, mapping, start_index); > > + > > + if (!S_ISREG(inode->i_mode)) > > + return -EOPNOTSUPP; > > + > > + /* Should be read only. */ > > + if (!(file->f_mode & FMODE_READ)) > > + return -EBADF; > > + > > + /* Do not support compressed file for large folio. */ > > + if (f2fs_compressed_file(inode)) > > + return -EINVAL; > > + > > + if (!mapping || len < 0) > > + return -EINVAL; > > + > > + if (unlikely(!mapping->a_ops->read_folio && !mapping->a_ops->readahead)) > > + return -EINVAL; > > + > > + /* Load extent cache at the first readahead. */ > > + f2fs_precache_extents(inode); > > + > > + /* > > + * Careful about overflows. Len == 0 means "as much as possible". Use > > + * unsigned math because signed overflows are undefined and UBSan > > + * complains. > > + */ > > + if (!len || endbyte > i_size_read(inode) || endbyte < len) > > + endbyte = i_size_read(inode) - 1; > > + else > > + endbyte--; /* inclusive */ > > + > > + /* First and last PARTIAL page! */ > > + end_index = endbyte >> PAGE_SHIFT; > > + > > + if (start_index > end_index) > > + return 0; > > + > > + nrpages = end_index - start_index + 1; > > + > > + while (nrpages) { > > + unsigned long this_chunk = min(nrpages, ra_pages); > > + > > + ractl.ra->ra_pages = this_chunk; > > + > > + page_cache_sync_ra(&ractl, this_chunk << 1); > > + > > + nrpages -= this_chunk; > > + } > > + return 0; > > +} > > + > > int f2fs_encrypt_one_page(struct f2fs_io_info *fio) > > { > > struct inode *inode = fio_inode(fio); > > diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h > > index 3340db04a7c2..934287cc5624 100644 > > --- a/fs/f2fs/f2fs.h > > +++ b/fs/f2fs/f2fs.h > > @@ -4047,6 +4047,7 @@ int f2fs_init_bio_entry_cache(void); > > void f2fs_destroy_bio_entry_cache(void); > > void f2fs_submit_read_bio(struct f2fs_sb_info *sbi, struct bio *bio, > > enum page_type type); > > +int f2fs_readahead_pages(struct file *file, loff_t offset, loff_t len); > > int f2fs_init_write_merge_io(struct f2fs_sb_info *sbi); > > void f2fs_submit_merged_write(struct f2fs_sb_info *sbi, enum page_type type); > > void f2fs_submit_merged_write_cond(struct f2fs_sb_info *sbi, > > diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c > > index d7047ca6b98d..b6f71efd6d2a 100644 > > --- a/fs/f2fs/file.c > > +++ b/fs/f2fs/file.c > > @@ -5305,9 +5305,12 @@ static int f2fs_file_fadvise(struct file *filp, loff_t offset, loff_t len, > > filp->f_mode &= ~FMODE_RANDOM; > > spin_unlock(&filp->f_lock); > > return 0; > > - } else if (advice == POSIX_FADV_WILLNEED && offset == 0) { > > - /* Load extent cache at the first readahead. */ > > - f2fs_precache_extents(inode); > > + } else if (advice == POSIX_FADV_WILLNEED) { > > + if (offset == 0 && len == -1) { > > + f2fs_precache_extents(inode); > > + return 0; > > + } > > + return f2fs_readahead_pages(filp, offset, len); > > } > > > > err = generic_fadvise(filp, offset, len, advice); > > -- > > 2.52.0.487.g5c8c507ade-goog > > > > > ---end quoted text---