diff options
Diffstat (limited to 'mm/filemap.c')
| -rw-r--r-- | mm/filemap.c | 54 |
1 files changed, 41 insertions, 13 deletions
diff --git a/mm/filemap.c b/mm/filemap.c index 807a463fd5ed..d504d6e98886 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -828,6 +828,32 @@ grab_cache_page_nowait(struct address_space *mapping, unsigned long index) } EXPORT_SYMBOL(grab_cache_page_nowait); +/* + * CD/DVDs are error prone. When a medium error occurs, the driver may fail + * a _large_ part of the i/o request. Imagine the worst scenario: + * + * ---R__________________________________________B__________ + * ^ reading here ^ bad block(assume 4k) + * + * read(R) => miss => readahead(R...B) => media error => frustrating retries + * => failing the whole request => read(R) => read(R+1) => + * readahead(R+1...B+1) => bang => read(R+2) => read(R+3) => + * readahead(R+3...B+2) => bang => read(R+3) => read(R+4) => + * readahead(R+4...B+3) => bang => read(R+4) => read(R+5) => ...... + * + * It is going insane. Fix it by quickly scaling down the readahead size. + */ +static void shrink_readahead_size_eio(struct file *filp, + struct file_ra_state *ra) +{ + if (!ra->ra_pages) + return; + + ra->ra_pages /= 4; + printk(KERN_WARNING "Reducing readahead size to %luK\n", + ra->ra_pages << (PAGE_CACHE_SHIFT - 10)); +} + /** * do_generic_mapping_read - generic file read routine * @mapping: address_space to be read @@ -985,6 +1011,7 @@ readpage: } unlock_page(page); error = -EIO; + shrink_readahead_size_eio(filp, &ra); goto readpage_error; } unlock_page(page); @@ -1522,6 +1549,7 @@ page_not_uptodate: * Things didn't work out. Return zero to tell the * mm layer so, possibly freeing the page cache page first. */ + shrink_readahead_size_eio(file, ra); page_cache_release(page); return NULL; } @@ -1892,7 +1920,7 @@ int remove_suid(struct dentry *dentry) EXPORT_SYMBOL(remove_suid); size_t -__filemap_copy_from_user_iovec(char *vaddr, +__filemap_copy_from_user_iovec_inatomic(char *vaddr, const struct iovec *iov, size_t base, size_t bytes) { size_t copied = 0, left = 0; @@ -1908,12 +1936,8 @@ __filemap_copy_from_user_iovec(char *vaddr, vaddr += copy; iov++; - if (unlikely(left)) { - /* zero the rest of the target like __copy_from_user */ - if (bytes) - memset(vaddr, 0, bytes); + if (unlikely(left)) break; - } } return copied - left; } @@ -2071,14 +2095,21 @@ generic_file_buffered_write(struct kiocb *iocb, const struct iovec *iov, do { unsigned long index; unsigned long offset; - unsigned long maxlen; size_t copied; offset = (pos & (PAGE_CACHE_SIZE -1)); /* Within page */ index = pos >> PAGE_CACHE_SHIFT; bytes = PAGE_CACHE_SIZE - offset; - if (bytes > count) - bytes = count; + + /* Limit the size of the copy to the caller's write size */ + bytes = min(bytes, count); + + /* + * Limit the size of the copy to that of the current segment, + * because fault_in_pages_readable() doesn't know how to walk + * segments. + */ + bytes = min(bytes, cur_iov->iov_len - iov_base); /* * Bring in the user page that we will copy from _first_. @@ -2086,10 +2117,7 @@ generic_file_buffered_write(struct kiocb *iocb, const struct iovec *iov, * same page as we're writing to, without it being marked * up-to-date. */ - maxlen = cur_iov->iov_len - iov_base; - if (maxlen > bytes) - maxlen = bytes; - fault_in_pages_readable(buf, maxlen); + fault_in_pages_readable(buf, bytes); page = __grab_cache_page(mapping,index,&cached_page,&lru_pvec); if (!page) { |
