[RFC,2/4] fs: factor out backing_file_{read,write}_iter() helpers

Message ID	20231221095410.801061-3-amir73il@gmail.com (mailing list archive)
State	New
Headers	show Received: from mail-wr1-f50.google.com (mail-wr1-f50.google.com [209.85.221.50]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B74EB4CB3E; Thu, 21 Dec 2023 09:54:18 +0000 (UTC) From: Amir Goldstein <amir73il@gmail.com> To: Christian Brauner <brauner@kernel.org>, Miklos Szeredi <miklos@szeredi.hu> Cc: linux-fsdevel@vger.kernel.org, linux-unionfs@vger.kernel.org Subject: [RFC][PATCH 2/4] fs: factor out backing_file_{read,write}_iter() helpers Date: Thu, 21 Dec 2023 11:54:08 +0200 Message-Id: <20231221095410.801061-3-amir73il@gmail.com> In-Reply-To: <20231221095410.801061-1-amir73il@gmail.com> References: <20231221095410.801061-1-amir73il@gmail.com> Precedence: bulk MIME-Version: 1.0 Content-Transfer-Encoding: 8bit
Series	Intruduce stacking filesystem vfs helpers \| expand [RFC,0/4] Intruduce stacking filesystem vfs helpers [RFC,1/4] fs: prepare for stackable filesystems backing file helpers [RFC,2/4] fs: factor out backing_file_{read,write}_iter() helpers [RFC,3/4] fs: factor out backing_file_splice_{read,write}() helpers [RFC,4/4] fs: factor out backing_file_mmap() helper

diff --git a/fs/backing-file.c b/fs/backing-file.c index 04b33036f709..c1976ef5c210 100644 --- a/fs/backing-file.c +++ b/fs/backing-file.c @@ -2,6 +2,9 @@ /* * Common helpers for stackable filesystems and backing files. * + * Forked from fs/overlayfs/file.c. + * + * Copyright (C) 2017 Red Hat, Inc. * Copyright (C) 2023 CTERA Networks. */ @@ -46,3 +49,204 @@ struct file *backing_file_open(const struct path *user_path, int flags, return f; } EXPORT_SYMBOL_GPL(backing_file_open); + +struct backing_aio { + struct kiocb iocb; + refcount_t ref; + struct kiocb *orig_iocb; + /* used for aio completion */ + void (*end_write)(struct file *); + struct work_struct work; + long res; +}; + +static struct kmem_cache *backing_aio_cachep; + +#define BACKING_IOCB_MASK \ + (IOCB_NOWAIT | IOCB_HIPRI | IOCB_DSYNC | IOCB_SYNC | IOCB_APPEND) + +static rwf_t iocb_to_rw_flags(int flags) +{ + return (__force rwf_t)(flags & BACKING_IOCB_MASK); +} + +static void backing_aio_put(struct backing_aio *aio) +{ + if (refcount_dec_and_test(&aio->ref)) { + fput(aio->iocb.ki_filp); + kmem_cache_free(backing_aio_cachep, aio); + } +} + +static void backing_aio_cleanup(struct backing_aio *aio, long res) +{ + struct kiocb *iocb = &aio->iocb; + struct kiocb *orig_iocb = aio->orig_iocb; + + if (aio->end_write) + aio->end_write(orig_iocb->ki_filp); + + orig_iocb->ki_pos = iocb->ki_pos; + backing_aio_put(aio); +} + +static void backing_aio_rw_complete(struct kiocb *iocb, long res) +{ + struct backing_aio *aio = container_of(iocb, struct backing_aio, iocb); + struct kiocb *orig_iocb = aio->orig_iocb; + + if (iocb->ki_flags & IOCB_WRITE) + kiocb_end_write(iocb); + + backing_aio_cleanup(aio, res); + orig_iocb->ki_complete(orig_iocb, res); +} + +static void backing_aio_complete_work(struct work_struct *work) +{ + struct backing_aio *aio = container_of(work, struct backing_aio, work); + + backing_aio_rw_complete(&aio->iocb, aio->res); +} + +static void backing_aio_queue_completion(struct kiocb *iocb, long res) +{ + struct backing_aio *aio = container_of(iocb, struct backing_aio, iocb); + + /* + * Punt to a work queue to serialize updates of mtime/size. + */ + aio->res = res; + INIT_WORK(&aio->work, backing_aio_complete_work); + queue_work(file_inode(aio->orig_iocb->ki_filp)->i_sb->s_dio_done_wq, + &aio->work); +} + +static int backing_aio_init_wq(struct kiocb *iocb) +{ + struct super_block *sb = file_inode(iocb->ki_filp)->i_sb; + + if (sb->s_dio_done_wq) + return 0; + + return sb_init_dio_done_wq(sb); +} + + +ssize_t backing_file_read_iter(struct file *file, struct iov_iter *iter, + struct kiocb *iocb, int flags, + struct backing_file_ctx *ctx) +{ + struct backing_aio *aio = NULL; + const struct cred *old_cred; + ssize_t ret; + + if (!iov_iter_count(iter)) + return 0; + + if (iocb->ki_flags & IOCB_DIRECT && + !(file->f_mode & FMODE_CAN_ODIRECT)) + return -EINVAL; + + old_cred = override_creds(ctx->cred); + if (is_sync_kiocb(iocb)) { + rwf_t rwf = iocb_to_rw_flags(flags); + + ret = vfs_iter_read(file, iter, &iocb->ki_pos, rwf); + } else { + ret = -ENOMEM; + aio = kmem_cache_zalloc(backing_aio_cachep, GFP_KERNEL); + if (!aio) + goto out; + + aio->orig_iocb = iocb; + kiocb_clone(&aio->iocb, iocb, get_file(file)); + aio->iocb.ki_complete = backing_aio_rw_complete; + refcount_set(&aio->ref, 2); + ret = vfs_iocb_iter_read(file, &aio->iocb, iter); + backing_aio_put(aio); + if (ret != -EIOCBQUEUED) + backing_aio_cleanup(aio, ret); + } +out: + revert_creds(old_cred); + + if (ctx->accessed) + ctx->accessed(ctx->user_file); + + return ret; +} +EXPORT_SYMBOL_GPL(backing_file_read_iter); + +ssize_t backing_file_write_iter(struct file *file, struct iov_iter *iter, + struct kiocb *iocb, int flags, + struct backing_file_ctx *ctx) +{ + const struct cred *old_cred; + ssize_t ret; + + if (!iov_iter_count(iter)) + return 0; + + ret = file_remove_privs(ctx->user_file); + if (ret) + return ret; + + if (iocb->ki_flags & IOCB_DIRECT && + !(file->f_mode & FMODE_CAN_ODIRECT)) + return -EINVAL; + + /* + * Stacked filesystems don't support deferred completions, don't copy + * this property in case it is set by the issuer. + */ + flags &= ~IOCB_DIO_CALLER_COMP; + + old_cred = override_creds(ctx->cred); + if (is_sync_kiocb(iocb)) { + rwf_t rwf = iocb_to_rw_flags(flags); + + ret = vfs_iter_write(file, iter, &iocb->ki_pos, rwf); + if (ctx->end_write) + ctx->end_write(ctx->user_file); + } else { + struct backing_aio *aio; + + ret = backing_aio_init_wq(iocb); + if (ret) + goto out; + + ret = -ENOMEM; + aio = kmem_cache_zalloc(backing_aio_cachep, GFP_KERNEL); + if (!aio) + goto out; + + aio->orig_iocb = iocb; + aio->end_write = ctx->end_write; + kiocb_clone(&aio->iocb, iocb, get_file(file)); + aio->iocb.ki_flags = flags; + aio->iocb.ki_complete = backing_aio_queue_completion; + refcount_set(&aio->ref, 2); + ret = vfs_iocb_iter_write(file, &aio->iocb, iter); + backing_aio_put(aio); + if (ret != -EIOCBQUEUED) + backing_aio_cleanup(aio, ret); + } +out: + revert_creds(old_cred); + + return ret; +} +EXPORT_SYMBOL_GPL(backing_file_write_iter); + +static int __init backing_aio_init(void) +{ + backing_aio_cachep = kmem_cache_create("backing_aio", + sizeof(struct backing_aio), + 0, SLAB_HWCACHE_ALIGN, NULL); + if (!backing_aio_cachep) + return -ENOMEM; + + return 0; +} +fs_initcall(backing_aio_init); diff --git a/fs/overlayfs/file.c b/fs/overlayfs/file.c index a6da3eaf6d4f..1b578cb27a26 100644 --- a/fs/overlayfs/file.c +++ b/fs/overlayfs/file.c @@ -16,19 +16,6 @@ #include <linux/backing-file.h> #include "overlayfs.h" -#include "../internal.h" /* for sb_init_dio_done_wq */ - -struct ovl_aio_req { - struct kiocb iocb; - refcount_t ref; - struct kiocb *orig_iocb; - /* used for aio completion */ - struct work_struct work; - long res; -}; - -static struct kmem_cache *ovl_aio_request_cachep; - static char ovl_whatisit(struct inode *inode, struct inode *realinode) { if (realinode != ovl_inode_upper(inode)) @@ -275,84 +262,16 @@ static void ovl_file_accessed(struct file *file) touch_atime(&file->f_path); } -#define OVL_IOCB_MASK \ - (IOCB_NOWAIT | IOCB_HIPRI | IOCB_DSYNC | IOCB_SYNC | IOCB_APPEND) - -static rwf_t iocb_to_rw_flags(int flags) -{ - return (__force rwf_t)(flags & OVL_IOCB_MASK); -} - -static inline void ovl_aio_put(struct ovl_aio_req *aio_req) -{ - if (refcount_dec_and_test(&aio_req->ref)) { - fput(aio_req->iocb.ki_filp); - kmem_cache_free(ovl_aio_request_cachep, aio_req); - } -} - -static void ovl_aio_cleanup_handler(struct ovl_aio_req *aio_req) -{ - struct kiocb *iocb = &aio_req->iocb; - struct kiocb *orig_iocb = aio_req->orig_iocb; - - if (iocb->ki_flags & IOCB_WRITE) - ovl_file_modified(orig_iocb->ki_filp); - - orig_iocb->ki_pos = iocb->ki_pos; - ovl_aio_put(aio_req); -} - -static void ovl_aio_rw_complete(struct kiocb *iocb, long res) -{ - struct ovl_aio_req *aio_req = container_of(iocb, - struct ovl_aio_req, iocb); - struct kiocb *orig_iocb = aio_req->orig_iocb; - - if (iocb->ki_flags & IOCB_WRITE) - kiocb_end_write(iocb); - - ovl_aio_cleanup_handler(aio_req); - orig_iocb->ki_complete(orig_iocb, res); -} - -static void ovl_aio_complete_work(struct work_struct *work) -{ - struct ovl_aio_req *aio_req = container_of(work, - struct ovl_aio_req, work); - - ovl_aio_rw_complete(&aio_req->iocb, aio_req->res); -} - -static void ovl_aio_queue_completion(struct kiocb *iocb, long res) -{ - struct ovl_aio_req *aio_req = container_of(iocb, - struct ovl_aio_req, iocb); - struct kiocb *orig_iocb = aio_req->orig_iocb; - - /* - * Punt to a work queue to serialize updates of mtime/size. - */ - aio_req->res = res; - INIT_WORK(&aio_req->work, ovl_aio_complete_work); - queue_work(file_inode(orig_iocb->ki_filp)->i_sb->s_dio_done_wq, - &aio_req->work); -} - -static int ovl_init_aio_done_wq(struct super_block *sb) -{ - if (sb->s_dio_done_wq) - return 0; - - return sb_init_dio_done_wq(sb); -} - static ssize_t ovl_read_iter(struct kiocb *iocb, struct iov_iter *iter) { struct file *file = iocb->ki_filp; struct fd real; - const struct cred *old_cred; ssize_t ret; + struct backing_file_ctx ctx = { + .cred = ovl_creds(file_inode(file)->i_sb), + .user_file = file, + .accessed = ovl_file_accessed, + }; if (!iov_iter_count(iter)) return 0; @@ -361,37 +280,8 @@ static ssize_t ovl_read_iter(struct kiocb *iocb, struct iov_iter *iter) if (ret) return ret; - ret = -EINVAL; - if (iocb->ki_flags & IOCB_DIRECT && - !(real.file->f_mode & FMODE_CAN_ODIRECT)) - goto out_fdput; - - old_cred = ovl_override_creds(file_inode(file)->i_sb); - if (is_sync_kiocb(iocb)) { - rwf_t rwf = iocb_to_rw_flags(iocb->ki_flags); - - ret = vfs_iter_read(real.file, iter, &iocb->ki_pos, rwf); - } else { - struct ovl_aio_req *aio_req; - - ret = -ENOMEM; - aio_req = kmem_cache_zalloc(ovl_aio_request_cachep, GFP_KERNEL); - if (!aio_req) - goto out; - - aio_req->orig_iocb = iocb; - kiocb_clone(&aio_req->iocb, iocb, get_file(real.file)); - aio_req->iocb.ki_complete = ovl_aio_rw_complete; - refcount_set(&aio_req->ref, 2); - ret = vfs_iocb_iter_read(real.file, &aio_req->iocb, iter); - ovl_aio_put(aio_req); - if (ret != -EIOCBQUEUED) - ovl_aio_cleanup_handler(aio_req); - } -out: - revert_creds(old_cred); - ovl_file_accessed(file); -out_fdput: + ret = backing_file_read_iter(real.file, iter, iocb, iocb->ki_flags, + &ctx); fdput(real); return ret; @@ -402,9 +292,13 @@ static ssize_t ovl_write_iter(struct kiocb *iocb, struct iov_iter *iter) struct file *file = iocb->ki_filp; struct inode *inode = file_inode(file); struct fd real; - const struct cred *old_cred; ssize_t ret; int ifl = iocb->ki_flags; + struct backing_file_ctx ctx = { + .cred = ovl_creds(inode->i_sb), + .user_file = file, + .end_write = ovl_file_modified, + }; if (!iov_iter_count(iter)) return 0; @@ -412,19 +306,11 @@ static ssize_t ovl_write_iter(struct kiocb *iocb, struct iov_iter *iter) inode_lock(inode); /* Update mode */ ovl_copyattr(inode); - ret = file_remove_privs(file); - if (ret) - goto out_unlock; ret = ovl_real_fdget(file, &real); if (ret) goto out_unlock; - ret = -EINVAL; - if (iocb->ki_flags & IOCB_DIRECT && - !(real.file->f_mode & FMODE_CAN_ODIRECT)) - goto out_fdput; - if (!ovl_should_sync(OVL_FS(inode->i_sb))) ifl &= ~(IOCB_DSYNC | IOCB_SYNC); @@ -433,39 +319,7 @@ static ssize_t ovl_write_iter(struct kiocb *iocb, struct iov_iter *iter) * this property in case it is set by the issuer. */ ifl &= ~IOCB_DIO_CALLER_COMP; - - old_cred = ovl_override_creds(file_inode(file)->i_sb); - if (is_sync_kiocb(iocb)) { - rwf_t rwf = iocb_to_rw_flags(ifl); - - ret = vfs_iter_write(real.file, iter, &iocb->ki_pos, rwf); - /* Update size */ - ovl_file_modified(file); - } else { - struct ovl_aio_req *aio_req; - - ret = ovl_init_aio_done_wq(inode->i_sb); - if (ret) - goto out; - - ret = -ENOMEM; - aio_req = kmem_cache_zalloc(ovl_aio_request_cachep, GFP_KERNEL); - if (!aio_req) - goto out; - - aio_req->orig_iocb = iocb; - kiocb_clone(&aio_req->iocb, iocb, get_file(real.file)); - aio_req->iocb.ki_flags = ifl; - aio_req->iocb.ki_complete = ovl_aio_queue_completion; - refcount_set(&aio_req->ref, 2); - ret = vfs_iocb_iter_write(real.file, &aio_req->iocb, iter); - ovl_aio_put(aio_req); - if (ret != -EIOCBQUEUED) - ovl_aio_cleanup_handler(aio_req); - } -out: - revert_creds(old_cred); -out_fdput: + ret = backing_file_write_iter(real.file, iter, iocb, ifl, &ctx); fdput(real); out_unlock: @@ -777,19 +631,3 @@ const struct file_operations ovl_file_operations = { .copy_file_range = ovl_copy_file_range, .remap_file_range = ovl_remap_file_range, }; - -int __init ovl_aio_request_cache_init(void) -{ - ovl_aio_request_cachep = kmem_cache_create("ovl_aio_req", - sizeof(struct ovl_aio_req), - 0, SLAB_HWCACHE_ALIGN, NULL); - if (!ovl_aio_request_cachep) - return -ENOMEM; - - return 0; -} - -void ovl_aio_request_cache_destroy(void) -{ - kmem_cache_destroy(ovl_aio_request_cachep); -} diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h index 05c3dd597fa8..5ba11eb43767 100644 --- a/fs/overlayfs/overlayfs.h +++ b/fs/overlayfs/overlayfs.h @@ -425,6 +425,12 @@ int ovl_want_write(struct dentry *dentry); void ovl_drop_write(struct dentry *dentry); struct dentry *ovl_workdir(struct dentry *dentry); const struct cred *ovl_override_creds(struct super_block *sb); + +static inline const struct cred *ovl_creds(struct super_block *sb) +{ + return OVL_FS(sb)->creator_cred; +} + int ovl_can_decode_fh(struct super_block *sb); struct dentry *ovl_indexdir(struct super_block *sb); bool ovl_index_all(struct super_block *sb); @@ -837,8 +843,6 @@ struct dentry *ovl_create_temp(struct ovl_fs *ofs, struct dentry *workdir, /* file.c */ extern const struct file_operations ovl_file_operations; -int __init ovl_aio_request_cache_init(void); -void ovl_aio_request_cache_destroy(void); int ovl_real_fileattr_get(const struct path *realpath, struct fileattr *fa); int ovl_real_fileattr_set(const struct path *realpath, struct fileattr *fa); int ovl_fileattr_get(struct dentry *dentry, struct fileattr *fa); diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c index 1d6b98dd9003..8ac4726795ce 100644 --- a/fs/overlayfs/super.c +++ b/fs/overlayfs/super.c @@ -1500,14 +1500,10 @@ static int __init ovl_init(void) if (ovl_inode_cachep == NULL) return -ENOMEM; - err = ovl_aio_request_cache_init(); - if (!err) { - err = register_filesystem(&ovl_fs_type); - if (!err) - return 0; + err = register_filesystem(&ovl_fs_type); + if (!err) + return 0; - ovl_aio_request_cache_destroy(); - } kmem_cache_destroy(ovl_inode_cachep); return err; @@ -1523,7 +1519,6 @@ static void __exit ovl_exit(void) */ rcu_barrier(); kmem_cache_destroy(ovl_inode_cachep); - ovl_aio_request_cache_destroy(); } module_init(ovl_init); diff --git a/include/linux/backing-file.h b/include/linux/backing-file.h index 55c9e804f780..0648d548a418 100644 --- a/include/linux/backing-file.h +++ b/include/linux/backing-file.h @@ -9,9 +9,24 @@ #define _LINUX_BACKING_FILE_H #include <linux/file.h> +#include <linux/uio.h> +#include <linux/fs.h> + +struct backing_file_ctx { + const struct cred *cred; + struct file *user_file; + void (*accessed)(struct file *); + void (*end_write)(struct file *); +}; struct file *backing_file_open(const struct path *user_path, int flags, const struct path *real_path, const struct cred *cred); +ssize_t backing_file_read_iter(struct file *file, struct iov_iter *iter, + struct kiocb *iocb, int flags, + struct backing_file_ctx *ctx); +ssize_t backing_file_write_iter(struct file *file, struct iov_iter *iter, + struct kiocb *iocb, int flags, + struct backing_file_ctx *ctx); #endif /* _LINUX_BACKING_FILE_H */

[RFC,2/4] fs: factor out backing_file_{read,write}_iter() helpers

Commit Message

Patch