| Message ID | 20180530100208.31490-4-hch@lst.de |
|---|---|
| State | Not Applicable, archived |
| Headers | show |
| Series | [1/3] fs: move page_cache_seek_hole_data to iomap.c | expand |
2018-05-30 12:02 GMT+02:00 Christoph Hellwig <hch@lst.de>: > This way the implementation doesn't depend on buffer_head internals. > > Signed-off-by: Christoph Hellwig <hch@lst.de> > --- > fs/iomap.c | 85 +++++++++++++++++++++++++----------------------------- > 1 file changed, 39 insertions(+), 46 deletions(-) > > diff --git a/fs/iomap.c b/fs/iomap.c > index e75153f52748..5b92243808d3 100644 > --- a/fs/iomap.c > +++ b/fs/iomap.c > @@ -794,36 +794,51 @@ int iomap_fiemap(struct inode *inode, struct fiemap_extent_info *fi, > } > EXPORT_SYMBOL_GPL(iomap_fiemap); > > -/* > - * Seek for SEEK_DATA / SEEK_HOLE within @page, starting at @lastoff. > - * > - * Returns the offset within the file on success, and -ENOENT otherwise. > - */ > -static loff_t > -page_seek_hole_data(struct page *page, loff_t lastoff, int whence) > +static bool > +page_seek_hole_data(struct inode *inode, struct page *page, loff_t *lastoff, > + int whence) > { > - loff_t offset = page_offset(page); > - struct buffer_head *bh, *head; > + const struct address_space_operations *ops = inode->i_mapping->a_ops; > + unsigned int bsize = i_blocksize(inode), off; > bool seek_data = whence == SEEK_DATA; > + loff_t poff = page_offset(page); > > - if (lastoff < offset) > - lastoff = offset; > - > - bh = head = page_buffers(page); > - do { > - offset += bh->b_size; > - if (lastoff >= offset) > - continue; > + if (WARN_ON_ONCE(*lastoff >= poff + PAGE_SIZE)) > + return false; > > + if (*lastoff < poff) { > /* > - * Any buffer with valid data in it should have BH_Uptodate set. > + * Last offset smaller than the start of the page means we found > + * a hole: > */ > - if (buffer_uptodate(bh) == seek_data) > - return lastoff; > + if (whence == SEEK_HOLE) > + return true; > + *lastoff = poff; > + } > + > + /* > + * Just check the page unless we can and should check block ranges: > + */ > + if (bsize == PAGE_SIZE || !ops->is_partially_uptodate) > + return PageUptodate(page) == seek_data; > > - lastoff = offset; > - } while ((bh = bh->b_this_page) != head); > - return -ENOENT; > + lock_page(page); > + if (unlikely(page->mapping != inode->i_mapping)) > + goto out_unlock_not_found; Not a regression, but I guess it would make more sense to treat the above as a hole. > + > + for (off = 0; off < PAGE_SIZE; off += bsize) { > + if ((*lastoff & ~PAGE_MASK) >= off + bsize) > + continue; > + if (ops->is_partially_uptodate(page, off, bsize) == seek_data) { > + unlock_page(page); > + return true; > + } > + *lastoff = poff + off + bsize; > + } > + > +out_unlock_not_found: > + unlock_page(page); > + return false; > } > > /* > @@ -860,30 +875,8 @@ page_cache_seek_hole_data(struct inode *inode, loff_t offset, loff_t length, > for (i = 0; i < nr_pages; i++) { > struct page *page = pvec.pages[i]; > > - /* > - * At this point, the page may be truncated or > - * invalidated (changing page->mapping to NULL), or > - * even swizzled back from swapper_space to tmpfs file > - * mapping. However, page->index will not change > - * because we have a reference on the page. > - * > - * If current page offset is beyond where we've ended, > - * we've found a hole. > - */ > - if (whence == SEEK_HOLE && > - lastoff < page_offset(page)) > + if (page_seek_hole_data(inode, page, &lastoff, whence)) > goto check_range; > - > - lock_page(page); > - if (likely(page->mapping == inode->i_mapping) && > - page_has_buffers(page)) { > - lastoff = page_seek_hole_data(page, lastoff, whence); > - if (lastoff >= 0) { > - unlock_page(page); > - goto check_range; > - } > - } > - unlock_page(page); > lastoff = page_offset(page) + PAGE_SIZE; > } > pagevec_release(&pvec); > -- > 2.17.0 Other than the above, these three patches look okay, and they have passed xfstests on gfs2. Reviewed-by: Andreas Gruenbacher <agruenba@redhat.com> Thanks, Andreas
On Wed, May 30, 2018 at 12:02:08PM +0200, Christoph Hellwig wrote: > This way the implementation doesn't depend on buffer_head internals. > > Signed-off-by: Christoph Hellwig <hch@lst.de> > --- > fs/iomap.c | 85 +++++++++++++++++++++++++----------------------------- > 1 file changed, 39 insertions(+), 46 deletions(-) > > diff --git a/fs/iomap.c b/fs/iomap.c > index e75153f52748..5b92243808d3 100644 > --- a/fs/iomap.c > +++ b/fs/iomap.c > @@ -794,36 +794,51 @@ int iomap_fiemap(struct inode *inode, struct fiemap_extent_info *fi, > } > EXPORT_SYMBOL_GPL(iomap_fiemap); > > -/* > - * Seek for SEEK_DATA / SEEK_HOLE within @page, starting at @lastoff. > - * > - * Returns the offset within the file on success, and -ENOENT otherwise. > - */ > -static loff_t > -page_seek_hole_data(struct page *page, loff_t lastoff, int whence) > +static bool > +page_seek_hole_data(struct inode *inode, struct page *page, loff_t *lastoff, > + int whence) Can we keep the comment explaining the return value? > { > - loff_t offset = page_offset(page); > - struct buffer_head *bh, *head; > + const struct address_space_operations *ops = inode->i_mapping->a_ops; > + unsigned int bsize = i_blocksize(inode), off; Split this into two lines. Otherwise looks fine. Reviewed-by: Dave Chinner <dchinner@redhat.com>
On Thu, May 31, 2018 at 09:00:38AM +1000, Dave Chinner wrote: > > -/* > > - * Seek for SEEK_DATA / SEEK_HOLE within @page, starting at @lastoff. > > - * > > - * Returns the offset within the file on success, and -ENOENT otherwise. > > - */ > > -static loff_t > > -page_seek_hole_data(struct page *page, loff_t lastoff, int whence) > > +static bool > > +page_seek_hole_data(struct inode *inode, struct page *page, loff_t *lastoff, > > + int whence) > > Can we keep the comment explaining the return value? The old comment isn't going to be correct. I've added back a changed comment, akthough I don't really think it helps. > > + const struct address_space_operations *ops = inode->i_mapping->a_ops; > > + unsigned int bsize = i_blocksize(inode), off; > > Split this into two lines. We've got a pattern here - I really like it that way..
diff --git a/fs/iomap.c b/fs/iomap.c index e75153f52748..5b92243808d3 100644 --- a/fs/iomap.c +++ b/fs/iomap.c @@ -794,36 +794,51 @@ int iomap_fiemap(struct inode *inode, struct fiemap_extent_info *fi, } EXPORT_SYMBOL_GPL(iomap_fiemap); -/* - * Seek for SEEK_DATA / SEEK_HOLE within @page, starting at @lastoff. - * - * Returns the offset within the file on success, and -ENOENT otherwise. - */ -static loff_t -page_seek_hole_data(struct page *page, loff_t lastoff, int whence) +static bool +page_seek_hole_data(struct inode *inode, struct page *page, loff_t *lastoff, + int whence) { - loff_t offset = page_offset(page); - struct buffer_head *bh, *head; + const struct address_space_operations *ops = inode->i_mapping->a_ops; + unsigned int bsize = i_blocksize(inode), off; bool seek_data = whence == SEEK_DATA; + loff_t poff = page_offset(page); - if (lastoff < offset) - lastoff = offset; - - bh = head = page_buffers(page); - do { - offset += bh->b_size; - if (lastoff >= offset) - continue; + if (WARN_ON_ONCE(*lastoff >= poff + PAGE_SIZE)) + return false; + if (*lastoff < poff) { /* - * Any buffer with valid data in it should have BH_Uptodate set. + * Last offset smaller than the start of the page means we found + * a hole: */ - if (buffer_uptodate(bh) == seek_data) - return lastoff; + if (whence == SEEK_HOLE) + return true; + *lastoff = poff; + } + + /* + * Just check the page unless we can and should check block ranges: + */ + if (bsize == PAGE_SIZE || !ops->is_partially_uptodate) + return PageUptodate(page) == seek_data; - lastoff = offset; - } while ((bh = bh->b_this_page) != head); - return -ENOENT; + lock_page(page); + if (unlikely(page->mapping != inode->i_mapping)) + goto out_unlock_not_found; + + for (off = 0; off < PAGE_SIZE; off += bsize) { + if ((*lastoff & ~PAGE_MASK) >= off + bsize) + continue; + if (ops->is_partially_uptodate(page, off, bsize) == seek_data) { + unlock_page(page); + return true; + } + *lastoff = poff + off + bsize; + } + +out_unlock_not_found: + unlock_page(page); + return false; } /* @@ -860,30 +875,8 @@ page_cache_seek_hole_data(struct inode *inode, loff_t offset, loff_t length, for (i = 0; i < nr_pages; i++) { struct page *page = pvec.pages[i]; - /* - * At this point, the page may be truncated or - * invalidated (changing page->mapping to NULL), or - * even swizzled back from swapper_space to tmpfs file - * mapping. However, page->index will not change - * because we have a reference on the page. - * - * If current page offset is beyond where we've ended, - * we've found a hole. - */ - if (whence == SEEK_HOLE && - lastoff < page_offset(page)) + if (page_seek_hole_data(inode, page, &lastoff, whence)) goto check_range; - - lock_page(page); - if (likely(page->mapping == inode->i_mapping) && - page_has_buffers(page)) { - lastoff = page_seek_hole_data(page, lastoff, whence); - if (lastoff >= 0) { - unlock_page(page); - goto check_range; - } - } - unlock_page(page); lastoff = page_offset(page) + PAGE_SIZE; } pagevec_release(&pvec);
This way the implementation doesn't depend on buffer_head internals. Signed-off-by: Christoph Hellwig <hch@lst.de> --- fs/iomap.c | 85 +++++++++++++++++++++++++----------------------------- 1 file changed, 39 insertions(+), 46 deletions(-)