From df0db3ecdb8fc942e9d812558b8e15ecd3e050b1 Mon Sep 17 00:00:00 2001 From: Andreas Gruenbacher Date: Tue, 30 Apr 2019 08:45:34 -0700 Subject: [PATCH] iomap: Add a page_prepare callback Move the page_done callback into a separate iomap_page_ops structure and add a page_prepare calback to be called before the next page is written to. In gfs2, we'll want to start a transaction in page_prepare and end it in page_done. Other filesystems that implement data journaling will require the same kind of mechanism. Signed-off-by: Andreas Gruenbacher Reviewed-by: Christoph Hellwig Reviewed-by: Jan Kara Reviewed-by: Darrick J. Wong Signed-off-by: Darrick J. Wong --- fs/gfs2/bmap.c | 15 ++++++++++----- fs/iomap.c | 36 ++++++++++++++++++++++++++---------- include/linux/iomap.h | 22 +++++++++++++++++----- 3 files changed, 53 insertions(+), 20 deletions(-) diff --git a/fs/gfs2/bmap.c b/fs/gfs2/bmap.c index 02b2646..f6d1a38 100644 --- a/fs/gfs2/bmap.c +++ b/fs/gfs2/bmap.c @@ -965,15 +965,20 @@ static void gfs2_write_unlock(struct inode *inode) gfs2_glock_dq_uninit(&ip->i_gh); } -static void gfs2_iomap_journaled_page_done(struct inode *inode, loff_t pos, - unsigned copied, struct page *page, - struct iomap *iomap) +static void gfs2_iomap_page_done(struct inode *inode, loff_t pos, + unsigned copied, struct page *page, + struct iomap *iomap) { struct gfs2_inode *ip = GFS2_I(inode); - gfs2_page_add_databufs(ip, page, offset_in_page(pos), copied); + if (page) + gfs2_page_add_databufs(ip, page, offset_in_page(pos), copied); } +static const struct iomap_page_ops gfs2_iomap_page_ops = { + .page_done = gfs2_iomap_page_done, +}; + static int gfs2_iomap_begin_write(struct inode *inode, loff_t pos, loff_t length, unsigned flags, struct iomap *iomap, @@ -1051,7 +1056,7 @@ static int gfs2_iomap_begin_write(struct inode *inode, loff_t pos, } } if (!gfs2_is_stuffed(ip) && gfs2_is_jdata(ip)) - iomap->page_done = gfs2_iomap_journaled_page_done; + iomap->page_ops = &gfs2_iomap_page_ops; return 0; out_trans_end: diff --git a/fs/iomap.c b/fs/iomap.c index e6453c1..fbfe20b 100644 --- a/fs/iomap.c +++ b/fs/iomap.c @@ -657,6 +657,7 @@ static int iomap_write_begin(struct inode *inode, loff_t pos, unsigned len, unsigned flags, struct page **pagep, struct iomap *iomap) { + const struct iomap_page_ops *page_ops = iomap->page_ops; pgoff_t index = pos >> PAGE_SHIFT; struct page *page; int status = 0; @@ -666,9 +667,17 @@ iomap_write_begin(struct inode *inode, loff_t pos, unsigned len, unsigned flags, if (fatal_signal_pending(current)) return -EINTR; + if (page_ops && page_ops->page_prepare) { + status = page_ops->page_prepare(inode, pos, len, iomap); + if (status) + return status; + } + page = grab_cache_page_write_begin(inode->i_mapping, index, flags); - if (!page) - return -ENOMEM; + if (!page) { + status = -ENOMEM; + goto out_no_page; + } if (iomap->type == IOMAP_INLINE) iomap_read_inline_data(inode, page, iomap); @@ -676,15 +685,21 @@ iomap_write_begin(struct inode *inode, loff_t pos, unsigned len, unsigned flags, status = __block_write_begin_int(page, pos, len, NULL, iomap); else status = __iomap_write_begin(inode, pos, len, page, iomap); - if (unlikely(status)) { - unlock_page(page); - put_page(page); - page = NULL; - iomap_write_failed(inode, pos, len); - } + if (unlikely(status)) + goto out_unlock; *pagep = page; + return 0; + +out_unlock: + unlock_page(page); + put_page(page); + iomap_write_failed(inode, pos, len); + +out_no_page: + if (page_ops && page_ops->page_done) + page_ops->page_done(inode, pos, 0, NULL, iomap); return status; } @@ -758,6 +773,7 @@ static int iomap_write_end(struct inode *inode, loff_t pos, unsigned len, unsigned copied, struct page *page, struct iomap *iomap) { + const struct iomap_page_ops *page_ops = iomap->page_ops; int ret; if (iomap->type == IOMAP_INLINE) { @@ -770,8 +786,8 @@ iomap_write_end(struct inode *inode, loff_t pos, unsigned len, } __generic_write_end(inode, pos, ret, page); - if (iomap->page_done) - iomap->page_done(inode, pos, copied, page, iomap); + if (page_ops && page_ops->page_done) + page_ops->page_done(inode, pos, copied, page, iomap); put_page(page); if (ret < len) diff --git a/include/linux/iomap.h b/include/linux/iomap.h index 0fefb54..2103b94 100644 --- a/include/linux/iomap.h +++ b/include/linux/iomap.h @@ -53,6 +53,8 @@ struct vm_fault; */ #define IOMAP_NULL_ADDR -1ULL /* addr is not valid */ +struct iomap_page_ops; + struct iomap { u64 addr; /* disk offset of mapping, bytes */ loff_t offset; /* file offset of mapping, bytes */ @@ -63,12 +65,22 @@ struct iomap { struct dax_device *dax_dev; /* dax_dev for dax operations */ void *inline_data; void *private; /* filesystem private */ + const struct iomap_page_ops *page_ops; +}; - /* - * Called when finished processing a page in the mapping returned in - * this iomap. At least for now this is only supported in the buffered - * write path. - */ +/* + * When a filesystem sets page_ops in an iomap mapping it returns, page_prepare + * and page_done will be called for each page written to. This only applies to + * buffered writes as unbuffered writes will not typically have pages + * associated with them. + * + * When page_prepare succeeds, page_done will always be called to do any + * cleanup work necessary. In that page_done call, @page will be NULL if the + * associated page could not be obtained. + */ +struct iomap_page_ops { + int (*page_prepare)(struct inode *inode, loff_t pos, unsigned len, + struct iomap *iomap); void (*page_done)(struct inode *inode, loff_t pos, unsigned copied, struct page *page, struct iomap *iomap); }; -- 2.7.4