From 994fc28c7b1e697ac56befe4aecabf23f0689f46 Mon Sep 17 00:00:00 2001 From: Zach Brown Date: Thu, 15 Dec 2005 14:28:17 -0800 Subject: [PATCH] add AOP_TRUNCATED_PAGE, prepend AOP_ to WRITEPAGE_ACTIVATE readpage(), prepare_write(), and commit_write() callers are updated to understand the special return code AOP_TRUNCATED_PAGE in the style of writepage() and WRITEPAGE_ACTIVATE. AOP_TRUNCATED_PAGE tells the caller that the callee has unlocked the page and that the operation should be tried again with a new page. OCFS2 uses this to detect and work around a lock inversion in its aop methods. There should be no change in behaviour for methods that don't return AOP_TRUNCATED_PAGE. WRITEPAGE_ACTIVATE is also prepended with AOP_ for consistency and they are made enums so that kerneldoc can be used to document their semantics. Signed-off-by: Zach Brown --- mm/filemap.c | 73 ++++++++++++++++++++++++++++++++++++++++------------------ mm/readahead.c | 15 +++++++----- mm/shmem.c | 2 +- mm/vmscan.c | 2 +- 4 files changed, 61 insertions(+), 31 deletions(-) (limited to 'mm') diff --git a/mm/filemap.c b/mm/filemap.c index 33a28bfde158a5..6e1d08a2b8b9e1 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -831,8 +831,13 @@ readpage: /* Start the actual read. The read will unlock the page. */ error = mapping->a_ops->readpage(filp, page); - if (unlikely(error)) + if (unlikely(error)) { + if (error == AOP_TRUNCATED_PAGE) { + page_cache_release(page); + goto find_page; + } goto readpage_error; + } if (!PageUptodate(page)) { lock_page(page); @@ -1152,26 +1157,24 @@ static int fastcall page_cache_read(struct file * file, unsigned long offset) { struct address_space *mapping = file->f_mapping; struct page *page; - int error; + int ret; - page = page_cache_alloc_cold(mapping); - if (!page) - return -ENOMEM; + do { + page = page_cache_alloc_cold(mapping); + if (!page) + return -ENOMEM; + + ret = add_to_page_cache_lru(page, mapping, offset, GFP_KERNEL); + if (ret == 0) + ret = mapping->a_ops->readpage(file, page); + else if (ret == -EEXIST) + ret = 0; /* losing race to add is OK */ - error = add_to_page_cache_lru(page, mapping, offset, GFP_KERNEL); - if (!error) { - error = mapping->a_ops->readpage(file, page); page_cache_release(page); - return error; - } - /* - * We arrive here in the unlikely event that someone - * raced with us and added our page to the cache first - * or we are out of memory for radix-tree nodes. - */ - page_cache_release(page); - return error == -EEXIST ? 0 : error; + } while (ret == AOP_TRUNCATED_PAGE); + + return ret; } #define MMAP_LOTSAMISS (100) @@ -1331,10 +1334,14 @@ page_not_uptodate: goto success; } - if (!mapping->a_ops->readpage(file, page)) { + error = mapping->a_ops->readpage(file, page); + if (!error) { wait_on_page_locked(page); if (PageUptodate(page)) goto success; + } else if (error == AOP_TRUNCATED_PAGE) { + page_cache_release(page); + goto retry_find; } /* @@ -1358,10 +1365,14 @@ page_not_uptodate: goto success; } ClearPageError(page); - if (!mapping->a_ops->readpage(file, page)) { + error = mapping->a_ops->readpage(file, page); + if (!error) { wait_on_page_locked(page); if (PageUptodate(page)) goto success; + } else if (error == AOP_TRUNCATED_PAGE) { + page_cache_release(page); + goto retry_find; } /* @@ -1444,10 +1455,14 @@ page_not_uptodate: goto success; } - if (!mapping->a_ops->readpage(file, page)) { + error = mapping->a_ops->readpage(file, page); + if (!error) { wait_on_page_locked(page); if (PageUptodate(page)) goto success; + } else if (error == AOP_TRUNCATED_PAGE) { + page_cache_release(page); + goto retry_find; } /* @@ -1470,10 +1485,14 @@ page_not_uptodate: } ClearPageError(page); - if (!mapping->a_ops->readpage(file, page)) { + error = mapping->a_ops->readpage(file, page); + if (!error) { wait_on_page_locked(page); if (PageUptodate(page)) goto success; + } else if (error == AOP_TRUNCATED_PAGE) { + page_cache_release(page); + goto retry_find; } /* @@ -1934,12 +1953,16 @@ generic_file_buffered_write(struct kiocb *iocb, const struct iovec *iov, status = a_ops->prepare_write(file, page, offset, offset+bytes); if (unlikely(status)) { loff_t isize = i_size_read(inode); + + if (status != AOP_TRUNCATED_PAGE) + unlock_page(page); + page_cache_release(page); + if (status == AOP_TRUNCATED_PAGE) + continue; /* * prepare_write() may have instantiated a few blocks * outside i_size. Trim these off again. */ - unlock_page(page); - page_cache_release(page); if (pos + bytes > isize) vmtruncate(inode, isize); break; @@ -1952,6 +1975,10 @@ generic_file_buffered_write(struct kiocb *iocb, const struct iovec *iov, cur_iov, iov_base, bytes); flush_dcache_page(page); status = a_ops->commit_write(file, page, offset, offset+bytes); + if (status == AOP_TRUNCATED_PAGE) { + page_cache_release(page); + continue; + } if (likely(copied > 0)) { if (!status) status = copied; diff --git a/mm/readahead.c b/mm/readahead.c index 72e7adbb87c7dd..8d6eeaaa6296f9 100644 --- a/mm/readahead.c +++ b/mm/readahead.c @@ -158,7 +158,7 @@ static int read_pages(struct address_space *mapping, struct file *filp, { unsigned page_idx; struct pagevec lru_pvec; - int ret = 0; + int ret; if (mapping->a_ops->readpages) { ret = mapping->a_ops->readpages(filp, mapping, pages, nr_pages); @@ -171,14 +171,17 @@ static int read_pages(struct address_space *mapping, struct file *filp, list_del(&page->lru); if (!add_to_page_cache(page, mapping, page->index, GFP_KERNEL)) { - mapping->a_ops->readpage(filp, page); - if (!pagevec_add(&lru_pvec, page)) - __pagevec_lru_add(&lru_pvec); - } else { - page_cache_release(page); + ret = mapping->a_ops->readpage(filp, page); + if (ret != AOP_TRUNCATED_PAGE) { + if (!pagevec_add(&lru_pvec, page)) + __pagevec_lru_add(&lru_pvec); + continue; + } /* else fall through to release */ } + page_cache_release(page); } pagevec_lru_add(&lru_pvec); + ret = 0; out: return ret; } diff --git a/mm/shmem.c b/mm/shmem.c index dc25565a61e95c..d9fc277940da54 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -855,7 +855,7 @@ unlock: swap_free(swap); redirty: set_page_dirty(page); - return WRITEPAGE_ACTIVATE; /* Return with the page locked */ + return AOP_WRITEPAGE_ACTIVATE; /* Return with the page locked */ } #ifdef CONFIG_NUMA diff --git a/mm/vmscan.c b/mm/vmscan.c index b0cd81c32de6ca..795a050fe4714c 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -367,7 +367,7 @@ static pageout_t pageout(struct page *page, struct address_space *mapping) res = mapping->a_ops->writepage(page, &wbc); if (res < 0) handle_write_error(mapping, page, res); - if (res == WRITEPAGE_ACTIVATE) { + if (res == AOP_WRITEPAGE_ACTIVATE) { ClearPageReclaim(page); return PAGE_ACTIVATE; } -- cgit 1.2.3-korg