From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id F25B83E3DB5; Wed, 15 Apr 2026 16:44:06 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776271447; cv=none; b=Non59mOgs3eYFP+v4pPiLfeosPwu5MQCF5nYpFpVm+E0RJFpHrOUtM/3CGHZf9aNSgldn5My0mgKMDiYBNIh35qyE2JadOR0cb+MZdnSis/W8ck0tMQpa5i3l6PvHk4NzdMcTtGOBT5BCJbv1FpywCGOVBW3VnyejSY8l0pAL3k= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776271447; c=relaxed/simple; bh=2XzfifibjGLTjaTgfDTA+z/KHXzhehAjX1QCcM/h0KE=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=ry6+WIKZ1wfkSnzr3KWlP5X4LhzrteEKmnKt1WE/VqGbwk8LW2oJ4MPHiyaDwNpSSb5N6BhIb4kWU/llpOAAyHNfzXBjQJwmhHsdNwJ4WhfDq7ATvipZFHgeVet4xrFAdMO3S8RlP2qB8JBfAyNwGcrou+Tesz2WQXMB/TDSbKQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=rbPWbt6O; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="rbPWbt6O" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5EEA3C19424; Wed, 15 Apr 2026 16:44:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1776271446; bh=2XzfifibjGLTjaTgfDTA+z/KHXzhehAjX1QCcM/h0KE=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=rbPWbt6OyaWAi9CXC7bhsK0GKQdJ23LbxAxGd56VF+vXifmLnZxT2cftnINp9l7XV d3Lu/FxsuvVwmk8Miv3CHh4X/4/dZZXSITIIkdpRw230ah6yD6sLECUlQjWUzYuMRK cJ8LggacmqB90gS/tHnOmc3RCsnk0A0tQufABU/aA2lZ+k08UmjMgOwfAJEHKOfsjG qkMfDi0NSMS4ZE6Wtw5F4NvNsAQDBM3U6iH2acLvwrQX2hluD6sNm+g3iWErispTQT tv4wEYoT/+siCHqi9dUAtkU6lgOC2n0F6qrGYiPIb2ZqujCEzc+hU+Lc2RqVV9ebyz B4RkELkEdVk6Q== Date: Wed, 15 Apr 2026 16:44:04 +0000 From: Jaegeuk Kim To: Christoph Hellwig Cc: linux-kernel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, Akilesh Kailash , linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-api@vger.kernel.org Subject: Re: [PATCH v2] f2fs: another way to set large folio by remembering inode number Message-ID: References: <20260409134538.3692605-1-jaegeuk@kernel.org> Precedence: bulk X-Mailing-List: linux-api@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On 04/14, Christoph Hellwig wrote: > Please add the relevant mailing lists when adding new user interfaces. > > And I'm not sure hacks working around the proper large folio > implementation are something that should be merged upstream. Cc'ed linux-api and linux-fsdevel onto the patch thread with a proposal that I'm not sure it's acceptable or not. > > On Fri, Apr 10, 2026 at 01:16:23AM +0000, Jaegeuk Kim wrote: > > enum { > > F2FS_XATTR_FADV_LARGEFOLIO, > > }; > > > > unsigned int value = BIT(F2FS_XATTR_FADV_LARGEFOLIO); > > > > 1. setxattr(file, "user.fadvise", &value, sizeof(unsigned int), 0) > > -> register the inode number for large folio > > 2. chmod(0400, file) > > -> make Read-Only > > 3. fsync() && close() && open(READ) > > -> f2fs_iget() with large folio > > 4. open(WRITE), mkwrite on mmap, chmod(WRITE) > > -> return error > > 5. close() and open() > > -> goto #3 > > 6. unlink > > -> deregister the inode number > > > > Suggested-by: Akilesh Kailash > > Signed-off-by: Jaegeuk Kim > > --- > > > > Log from v1: > > - add a condition in f2fs_drop_inode > > - add Doc > > > > Documentation/filesystems/f2fs.rst | 41 ++++++++++++++++++++++++++---- > > fs/f2fs/checkpoint.c | 2 +- > > fs/f2fs/data.c | 2 +- > > fs/f2fs/f2fs.h | 1 + > > fs/f2fs/file.c | 11 ++++++-- > > fs/f2fs/inode.c | 19 +++++++++++--- > > fs/f2fs/super.c | 7 +++++ > > fs/f2fs/xattr.c | 35 ++++++++++++++++++++++++- > > fs/f2fs/xattr.h | 6 +++++ > > 9 files changed, 111 insertions(+), 13 deletions(-) > > > > diff --git a/Documentation/filesystems/f2fs.rst b/Documentation/filesystems/f2fs.rst > > index 7e4031631286..de899d0d3088 100644 > > --- a/Documentation/filesystems/f2fs.rst > > +++ b/Documentation/filesystems/f2fs.rst > > @@ -1044,11 +1044,14 @@ page allocation for significant performance gains. To minimize code complexity, > > this support is currently excluded from the write path, which requires handling > > complex optimizations such as compression and block allocation modes. > > > > -This optional feature is triggered only when a file's immutable bit is set. > > -Consequently, F2FS will return EOPNOTSUPP if a user attempts to open a cached > > -file with write permissions, even immediately after clearing the bit. Write > > -access is only restored once the cached inode is dropped. The usage flow is > > -demonstrated below: > > +This optional feature is triggered by two mechanisms: the file's immutable bit > > +or a specific xattr flag. In both cases, F2FS ensures data integrity by > > +restricting the file to a read-only state while large folios are active. > > + > > +1. Immutable Bit Approach: > > +Triggered when the FS_IMMUTABLE_FL is set. This is a strict enforcement > > +where the file cannot be modified at all until the bit is cleared and > > +the cached inode is dropped. > > > > .. code-block:: > > > > @@ -1078,3 +1081,31 @@ demonstrated below: > > Written 4096 bytes with pattern = zero, total_time = 29 us, max_latency = 28 us > > > > # rm /data/testfile_read_seq > > + > > +2. XATTR fadvise Approach: > > +A more flexible registration via extended attributes. > > + > > +.. code-block:: > > + > > + enum { > > + F2FS_XATTR_FADV_LARGEFOLIO, > > + }; > > + unsigned int value = BIT(F2FS_XATTR_FADV_LARGEFOLIO); > > + > > + /* Registers the inode number for large folio support in the subsystem.*/ > > + # setxattr(file, "user.fadvise", &value, sizeof(unsigned int), 0) > > + > > + /* The file must be made Read-Only to transition into the large folio path. */ > > + # fchmod(0400, fd) > > + > > + /* clean up dirty inode state. */ > > + # fsync(fd) > > + > > + /* Drop the inode cache. > > + # close(fd) > > + > > + /* f2fs_iget() instantiates the inode with large folio support.*/ > > + # open() > > + > > + /* Returns -EOPNOTSUPP or error to protect the large folio cache.*/ > > + # open(WRITE), mkwrite on mmap, or chmod(WRITE) > > diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c > > index 01e1ba77263e..fdd62ddc3ed6 100644 > > --- a/fs/f2fs/checkpoint.c > > +++ b/fs/f2fs/checkpoint.c > > @@ -778,7 +778,7 @@ void f2fs_remove_ino_entry(struct f2fs_sb_info *sbi, nid_t ino, int type) > > __remove_ino_entry(sbi, ino, type); > > } > > > > -/* mode should be APPEND_INO, UPDATE_INO or TRANS_DIR_INO */ > > +/* mode should be APPEND_INO, UPDATE_INO, LARGE_FOLIO_IO, or TRANS_DIR_INO */ > > bool f2fs_exist_written_data(struct f2fs_sb_info *sbi, nid_t ino, int mode) > > { > > struct inode_management *im = &sbi->im[mode]; > > diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c > > index 965d4e6443c6..5e46230398d7 100644 > > --- a/fs/f2fs/data.c > > +++ b/fs/f2fs/data.c > > @@ -2494,7 +2494,7 @@ static int f2fs_read_data_large_folio(struct inode *inode, > > int ret = 0; > > bool folio_in_bio; > > > > - if (!IS_IMMUTABLE(inode) || f2fs_compressed_file(inode)) { > > + if (f2fs_compressed_file(inode)) { > > if (folio) > > folio_unlock(folio); > > return -EOPNOTSUPP; > > diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h > > index e40b6b2784ee..02bc6eb96a59 100644 > > --- a/fs/f2fs/f2fs.h > > +++ b/fs/f2fs/f2fs.h > > @@ -381,6 +381,7 @@ enum { > > /* for the list of ino */ > > enum { > > ORPHAN_INO, /* for orphan ino list */ > > + LARGE_FOLIO_INO, /* for large folio case */ > > APPEND_INO, /* for append ino list */ > > UPDATE_INO, /* for update ino list */ > > TRANS_DIR_INO, /* for transactions dir ino list */ > > diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c > > index c0220cd7b332..64ba900410fc 100644 > > --- a/fs/f2fs/file.c > > +++ b/fs/f2fs/file.c > > @@ -2068,9 +2068,16 @@ static long f2fs_fallocate(struct file *file, int mode, > > > > static int f2fs_release_file(struct inode *inode, struct file *filp) > > { > > - if (atomic_dec_and_test(&F2FS_I(inode)->open_count)) > > + if (atomic_dec_and_test(&F2FS_I(inode)->open_count)) { > > f2fs_remove_donate_inode(inode); > > - > > + /* > > + * In order to get large folio as soon as possible, let's drop > > + * inode cache asap. See also f2fs_drop_inode. > > + */ > > + if (f2fs_exist_written_data(F2FS_I_SB(inode), > > + inode->i_ino, LARGE_FOLIO_INO)) > > + d_drop(filp->f_path.dentry); > > + } > > /* > > * f2fs_release_file is called at every close calls. So we should > > * not drop any inmemory pages by close called by other process. > > diff --git a/fs/f2fs/inode.c b/fs/f2fs/inode.c > > index 89240be8cc59..e100bc5a378c 100644 > > --- a/fs/f2fs/inode.c > > +++ b/fs/f2fs/inode.c > > @@ -565,6 +565,20 @@ static bool is_meta_ino(struct f2fs_sb_info *sbi, unsigned int ino) > > ino == F2FS_COMPRESS_INO(sbi); > > } > > > > +static void f2fs_mapping_set_large_folio(struct inode *inode) > > +{ > > + struct f2fs_sb_info *sbi = F2FS_I_SB(inode); > > + > > + if (f2fs_compressed_file(inode)) > > + return; > > + if (f2fs_quota_file(sbi, inode->i_ino)) > > + return; > > + if (IS_IMMUTABLE(inode) || > > + (f2fs_exist_written_data(sbi, inode->i_ino, LARGE_FOLIO_INO) && > > + !(inode->i_mode & S_IWUGO))) > > + mapping_set_folio_min_order(inode->i_mapping, 0); > > +} > > + > > struct inode *f2fs_iget(struct super_block *sb, unsigned long ino) > > { > > struct f2fs_sb_info *sbi = F2FS_SB(sb); > > @@ -620,9 +634,7 @@ struct inode *f2fs_iget(struct super_block *sb, unsigned long ino) > > inode->i_op = &f2fs_file_inode_operations; > > inode->i_fop = &f2fs_file_operations; > > inode->i_mapping->a_ops = &f2fs_dblock_aops; > > - if (IS_IMMUTABLE(inode) && !f2fs_compressed_file(inode) && > > - !f2fs_quota_file(sbi, inode->i_ino)) > > - mapping_set_folio_min_order(inode->i_mapping, 0); > > + f2fs_mapping_set_large_folio(inode); > > } else if (S_ISDIR(inode->i_mode)) { > > inode->i_op = &f2fs_dir_inode_operations; > > inode->i_fop = &f2fs_dir_operations; > > @@ -895,6 +907,7 @@ void f2fs_evict_inode(struct inode *inode) > > f2fs_remove_ino_entry(sbi, inode->i_ino, APPEND_INO); > > f2fs_remove_ino_entry(sbi, inode->i_ino, UPDATE_INO); > > f2fs_remove_ino_entry(sbi, inode->i_ino, FLUSH_INO); > > + f2fs_remove_ino_entry(sbi, inode->i_ino, LARGE_FOLIO_INO); > > > > if (!is_sbi_flag_set(sbi, SBI_IS_FREEZING)) { > > sb_start_intwrite(inode->i_sb); > > diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c > > index ccf806b676f5..11d1e0c99ac1 100644 > > --- a/fs/f2fs/super.c > > +++ b/fs/f2fs/super.c > > @@ -1844,6 +1844,13 @@ static int f2fs_drop_inode(struct inode *inode) > > return 1; > > } > > } > > + /* > > + * In order to get large folio as soon as possible, let's drop > > + * inode cache asap. See also f2fs_release_file. > > + */ > > + if (f2fs_exist_written_data(sbi, inode->i_ino, LARGE_FOLIO_INO) && > > + !is_inode_flag_set(inode, FI_DIRTY_INODE)) > > + return 1; > > > > /* > > * This is to avoid a deadlock condition like below. > > diff --git a/fs/f2fs/xattr.c b/fs/f2fs/xattr.c > > index 941dc62a6d6f..0c0e44c2dcdd 100644 > > --- a/fs/f2fs/xattr.c > > +++ b/fs/f2fs/xattr.c > > @@ -44,6 +44,16 @@ static void xattr_free(struct f2fs_sb_info *sbi, void *xattr_addr, > > kfree(xattr_addr); > > } > > > > +static int f2fs_xattr_fadvise_get(struct inode *inode, void *buffer) > > +{ > > + if (!buffer) > > + goto out; > > + if (mapping_large_folio_support(inode->i_mapping)) > > + *((unsigned int *)buffer) |= BIT(F2FS_XATTR_FADV_LARGEFOLIO); > > +out: > > + return sizeof(unsigned int); > > +} > > + > > static int f2fs_xattr_generic_get(const struct xattr_handler *handler, > > struct dentry *unused, struct inode *inode, > > const char *name, void *buffer, size_t size) > > @@ -61,10 +71,29 @@ static int f2fs_xattr_generic_get(const struct xattr_handler *handler, > > default: > > return -EINVAL; > > } > > + if (handler->flags == F2FS_XATTR_INDEX_USER && > > + !strcmp(name, "fadvise")) > > + return f2fs_xattr_fadvise_get(inode, buffer); > > + > > return f2fs_getxattr(inode, handler->flags, name, > > buffer, size, NULL); > > } > > > > +static int f2fs_xattr_fadvise_set(struct inode *inode, const void *value) > > +{ > > + unsigned int new_fadvise; > > + > > + new_fadvise = *(unsigned int *)value; > > + > > + if (new_fadvise & BIT(F2FS_XATTR_FADV_LARGEFOLIO)) > > + f2fs_add_ino_entry(F2FS_I_SB(inode), > > + inode->i_ino, LARGE_FOLIO_INO); > > + else > > + f2fs_remove_ino_entry(F2FS_I_SB(inode), > > + inode->i_ino, LARGE_FOLIO_INO); > > + return 0; > > +} > > + > > static int f2fs_xattr_generic_set(const struct xattr_handler *handler, > > struct mnt_idmap *idmap, > > struct dentry *unused, struct inode *inode, > > @@ -84,6 +113,10 @@ static int f2fs_xattr_generic_set(const struct xattr_handler *handler, > > default: > > return -EINVAL; > > } > > + if (handler->flags == F2FS_XATTR_INDEX_USER && > > + !strcmp(name, "fadvise")) > > + return f2fs_xattr_fadvise_set(inode, value); > > + > > return f2fs_setxattr(inode, handler->flags, name, > > value, size, NULL, flags); > > } > > @@ -842,4 +875,4 @@ int __init f2fs_init_xattr_cache(void) > > void f2fs_destroy_xattr_cache(void) > > { > > kmem_cache_destroy(inline_xattr_slab); > > -} > > \ No newline at end of file > > +} > > diff --git a/fs/f2fs/xattr.h b/fs/f2fs/xattr.h > > index bce3d93e4755..455f460d014e 100644 > > --- a/fs/f2fs/xattr.h > > +++ b/fs/f2fs/xattr.h > > @@ -24,6 +24,7 @@ > > #define F2FS_XATTR_REFCOUNT_MAX 1024 > > > > /* Name indexes */ > > +#define F2FS_USER_FADVISE_NAME "user.fadvise" > > #define F2FS_SYSTEM_ADVISE_NAME "system.advise" > > #define F2FS_XATTR_INDEX_USER 1 > > #define F2FS_XATTR_INDEX_POSIX_ACL_ACCESS 2 > > @@ -39,6 +40,11 @@ > > #define F2FS_XATTR_NAME_ENCRYPTION_CONTEXT "c" > > #define F2FS_XATTR_NAME_VERITY "v" > > > > +/* used for F2FS_USER_FADVISE_NAME */ > > +enum { > > + F2FS_XATTR_FADV_LARGEFOLIO, > > +}; > > + > > struct f2fs_xattr_header { > > __le32 h_magic; /* magic number for identification */ > > __le32 h_refcount; /* reference count */ > > -- > > 2.53.0.1213.gd9a14994de-goog > > > > > ---end quoted text---