do_mmap_pgoff's PROT_EXEC do_page_cache_readahead assumes that is
implemented for all mappings, but not all filesystems provide ->readpage.
madvise_willneed (in mainline 2.5.72) makes the same assumption.
They don't reach oops because fault needs down_read on mmap_sem,
already held down_write; ps hangs, others may hang waiting for page lock.
Add page_cache_readahead_implemented, also testing for ->readpages,
since read_pages would also work on an a_ops with just ->readpages.
--- 2.5.72-mm3/include/linux/mm.h Sun Jun 22 11:51:40 2003
+++ linux/include/linux/mm.h Sun Jun 22 17:16:05 2003
@@ -568,6 +568,7 @@
#define VM_MAX_READAHEAD 128 /* kbytes */
#define VM_MIN_READAHEAD 16 /* kbytes (includes current page) */
+int page_cache_readahead_implemented(struct address_space *mapping);
int do_page_cache_readahead(struct address_space *mapping, struct file *filp,
unsigned long offset, unsigned long nr_to_read);
void page_cache_readahead(struct address_space *mapping,
--- 2.5.72-mm3/mm/fadvise.c Tue Apr 22 16:27:50 2003
+++ linux/mm/fadvise.c Sun Jun 22 17:16:05 2003
@@ -52,7 +52,7 @@
break;
case POSIX_FADV_WILLNEED:
case POSIX_FADV_NOREUSE:
- if (!mapping->a_ops->readpage) {
+ if (!page_cache_readahead_implemented(mapping)) {
ret = -EINVAL;
break;
}
--- 2.5.72-mm3/mm/filemap.c Sun Jun 22 11:51:40 2003
+++ linux/mm/filemap.c Sun Jun 22 17:16:05 2003
@@ -936,17 +936,6 @@
return desc.error;
}
-static ssize_t
-do_readahead(struct address_space *mapping, struct file *filp,
- unsigned long index, unsigned long nr)
-{
- if (!mapping || !mapping->a_ops || !mapping->a_ops->readpage)
- return -EINVAL;
-
- do_page_cache_readahead(mapping, filp, index, max_sane_readahead(nr));
- return 0;
-}
-
asmlinkage ssize_t sys_readahead(int fd, loff_t offset, size_t count)
{
ssize_t ret;
@@ -960,7 +949,13 @@
unsigned long start = offset >> PAGE_CACHE_SHIFT;
unsigned long end = (offset + count - 1) >> PAGE_CACHE_SHIFT;
unsigned long len = end - start + 1;
- ret = do_readahead(mapping, file, start, len);
+
+ if (page_cache_readahead_implemented(mapping)) {
+ do_page_cache_readahead(mapping, file, start,
+ max_sane_readahead(len));
+ ret = 0;
+ } else
+ ret = -EINVAL;
}
fput(file);
}
--- 2.5.72-mm3/mm/madvise.c Fri Dec 27 14:04:41 2002
+++ linux/mm/madvise.c Sun Jun 22 17:16:05 2003
@@ -56,6 +56,7 @@
unsigned long start, unsigned long end)
{
struct file *file = vma->vm_file;
+ struct address_space *mapping;
if (!file)
return -EBADF;
@@ -65,8 +66,11 @@
end = vma->vm_end;
end = ((end - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
- do_page_cache_readahead(file->f_dentry->d_inode->i_mapping,
- file, start, max_sane_readahead(end - start));
+ mapping = file->f_dentry->d_inode->i_mapping;
+ if (page_cache_readahead_implemented(mapping)) {
+ do_page_cache_readahead(mapping, file, start,
+ max_sane_readahead(end - start));
+ }
return 0;
}
--- 2.5.72-mm3/mm/mmap.c Sun Jun 22 11:51:40 2003
+++ linux/mm/mmap.c Sun Jun 22 17:16:05 2003
@@ -749,7 +749,7 @@
* that everything we want is in pagecache anyway.
*/
mapping = file->f_dentry->d_inode->i_mapping;
- if ( mapping &&
+ if ( page_cache_readahead_implemented(mapping) &&
((len >> PAGE_CACHE_SHIFT) > mapping->nrpages) &&
(len < 8 * 1024 * 1024)) {
do_page_cache_readahead(mapping, file, pgoff,
--- 2.5.72-mm3/mm/readahead.c Sun Jun 22 11:51:40 2003
+++ linux/mm/readahead.c Sun Jun 22 17:16:05 2003
@@ -523,3 +523,13 @@
get_zone_counts(&active, &inactive, &free);
return min(nr, (inactive + free) / 2);
}
+
+/*
+ * Check if page cache readahead is implemented on this mapping before
+ * calling do_page_cache_readahead (filemap can assume it's implemented).
+ */
+int page_cache_readahead_implemented(struct address_space *mapping)
+{
+ return mapping && mapping->a_ops &&
+ (mapping->a_ops->readpage || mapping->a_ops->readpages);
+}
-
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This archive was generated by hypermail 2b29 : Mon Jun 23 2003 - 22:00:38 EST