diff options
Diffstat (limited to 'Documentation/filesystems/vfs.rst')
| -rw-r--r-- | Documentation/filesystems/vfs.rst | 62 |
1 files changed, 33 insertions, 29 deletions
diff --git a/Documentation/filesystems/vfs.rst b/Documentation/filesystems/vfs.rst index bf5c48066fac..4f14edf93941 100644 --- a/Documentation/filesystems/vfs.rst +++ b/Documentation/filesystems/vfs.rst @@ -658,7 +658,7 @@ pages, however the address_space has finer control of write sizes. The read process essentially only requires 'readpage'. The write process is more complicated and uses write_begin/write_end or -set_page_dirty to write data into the address_space, and writepage and +dirty_folio to write data into the address_space, and writepage and writepages to writeback data to storage. Adding and removing pages to/from an address_space is protected by the @@ -724,7 +724,7 @@ cache in your filesystem. The following members are defined: int (*writepage)(struct page *page, struct writeback_control *wbc); int (*readpage)(struct file *, struct page *); int (*writepages)(struct address_space *, struct writeback_control *); - int (*set_page_dirty)(struct page *page); + bool (*dirty_folio)(struct address_space *, struct folio *); void (*readahead)(struct readahead_control *); int (*readpages)(struct file *filp, struct address_space *mapping, struct list_head *pages, unsigned nr_pages); @@ -735,7 +735,7 @@ cache in your filesystem. The following members are defined: loff_t pos, unsigned len, unsigned copied, struct page *page, void *fsdata); sector_t (*bmap)(struct address_space *, sector_t); - void (*invalidatepage) (struct page *, unsigned int, unsigned int); + void (*invalidate_folio) (struct folio *, size_t start, size_t len); int (*releasepage) (struct page *, int); void (*freepage)(struct page *); ssize_t (*direct_IO)(struct kiocb *, struct iov_iter *iter); @@ -745,10 +745,10 @@ cache in your filesystem. The following members are defined: int (*migratepage) (struct page *, struct page *); /* put migration-failed page back to right list */ void (*putback_page) (struct page *); - int (*launder_page) (struct page *); + int (*launder_folio) (struct folio *); - int (*is_partially_uptodate) (struct page *, unsigned long, - unsigned long); + bool (*is_partially_uptodate) (struct folio *, size_t from, + size_t count); void (*is_dirty_writeback) (struct page *, bool *, bool *); int (*error_remove_page) (struct mapping *mapping, struct page *page); int (*swap_activate)(struct file *); @@ -793,25 +793,29 @@ cache in your filesystem. The following members are defined: This will choose pages from the address space that are tagged as DIRTY and will pass them to ->writepage. -``set_page_dirty`` - called by the VM to set a page dirty. This is particularly - needed if an address space attaches private data to a page, and - that data needs to be updated when a page is dirtied. This is +``dirty_folio`` + called by the VM to mark a folio as dirty. This is particularly + needed if an address space attaches private data to a folio, and + that data needs to be updated when a folio is dirtied. This is called, for example, when a memory mapped page gets modified. - If defined, it should set the PageDirty flag, and the - PAGECACHE_TAG_DIRTY tag in the radix tree. + If defined, it should set the folio dirty flag, and the + PAGECACHE_TAG_DIRTY search mark in i_pages. ``readahead`` Called by the VM to read pages associated with the address_space object. The pages are consecutive in the page cache and are locked. The implementation should decrement the page refcount after starting I/O on each page. Usually the page will be - unlocked by the I/O completion handler. If the filesystem decides - to stop attempting I/O before reaching the end of the readahead - window, it can simply return. The caller will decrement the page - refcount and unlock the remaining pages for you. Set PageUptodate - if the I/O completes successfully. Setting PageError on any page - will be ignored; simply unlock the page if an I/O error occurs. + unlocked by the I/O completion handler. The set of pages are + divided into some sync pages followed by some async pages, + rac->ra->async_size gives the number of async pages. The + filesystem should attempt to read all sync pages but may decide + to stop once it reaches the async pages. If it does decide to + stop attempting I/O, it can simply return. The caller will + remove the remaining pages from the address space, unlock them + and decrement the page refcount. Set PageUptodate if the I/O + completes successfully. Setting PageError on any page will be + ignored; simply unlock the page if an I/O error occurs. ``readpages`` called by the VM to read pages associated with the address_space @@ -868,15 +872,15 @@ cache in your filesystem. The following members are defined: to find out where the blocks in the file are and uses those addresses directly. -``invalidatepage`` - If a page has PagePrivate set, then invalidatepage will be - called when part or all of the page is to be removed from the +``invalidate_folio`` + If a folio has private data, then invalidate_folio will be + called when part or all of the folio is to be removed from the address space. This generally corresponds to either a truncation, punch hole or a complete invalidation of the address space (in the latter case 'offset' will always be 0 and 'length' - will be PAGE_SIZE). Any private data associated with the page + will be folio_size()). Any private data associated with the page should be updated to reflect this truncation. If offset is 0 - and length is PAGE_SIZE, then the private data should be + and length is folio_size(), then the private data should be released, because the page must be able to be completely discarded. This may be done by calling the ->releasepage function, but in this case the release MUST succeed. @@ -930,16 +934,16 @@ cache in your filesystem. The following members are defined: ``putback_page`` Called by the VM when isolated page's migration fails. -``launder_page`` - Called before freeing a page - it writes back the dirty page. - To prevent redirtying the page, it is kept locked during the +``launder_folio`` + Called before freeing a folio - it writes back the dirty folio. + To prevent redirtying the folio, it is kept locked during the whole operation. ``is_partially_uptodate`` Called by the VM when reading a file through the pagecache when - the underlying blocksize != pagesize. If the required block is - up to date then the read can complete without needing the IO to - bring the whole page up to date. + the underlying blocksize is smaller than the size of the folio. + If the required block is up to date then the read can complete + without needing I/O to bring the whole page up to date. ``is_dirty_writeback`` Called by the VM when attempting to reclaim a page. The VM uses |