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authorLinus Torvalds <torvalds@g5.osdl.org>2005-08-19 18:02:56 -0700
committerLinus Torvalds <torvalds@g5.osdl.org>2005-08-19 18:02:56 -0700
commitcc314eef0128a807e50fa03baf2d0abc0647952c (patch)
tree8e38db1be28006894915273b3f3cb3beaa6efda3 /mm
parent2fb1e3086df9b454538491fba8121298da37cd23 (diff)
downloadlinux-linaro-cc314eef0128a807e50fa03baf2d0abc0647952c.tar.gz
Fix nasty ncpfs symlink handling bug.
This bug could cause oopses and page state corruption, because ncpfs used the generic page-cache symlink handlign functions. But those functions only work if the page cache is guaranteed to be "stable", ie a page that was installed when the symlink walk was started has to still be installed in the page cache at the end of the walk. We could have fixed ncpfs to not use the generic helper routines, but it is in many ways much cleaner to instead improve on the symlink walking helper routines so that they don't require that absolute stability. We do this by allowing "follow_link()" to return a error-pointer as a cookie, which is fed back to the cleanup "put_link()" routine. This also simplifies NFS symlink handling. Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/shmem.c17
1 files changed, 6 insertions, 11 deletions
diff --git a/mm/shmem.c b/mm/shmem.c
index e64fa726a79..5a81b1ee4f7 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -1773,32 +1773,27 @@ static int shmem_symlink(struct inode *dir, struct dentry *dentry, const char *s
return 0;
}
-static int shmem_follow_link_inline(struct dentry *dentry, struct nameidata *nd)
+static void *shmem_follow_link_inline(struct dentry *dentry, struct nameidata *nd)
{
nd_set_link(nd, (char *)SHMEM_I(dentry->d_inode));
- return 0;
+ return NULL;
}
-static int shmem_follow_link(struct dentry *dentry, struct nameidata *nd)
+static void *shmem_follow_link(struct dentry *dentry, struct nameidata *nd)
{
struct page *page = NULL;
int res = shmem_getpage(dentry->d_inode, 0, &page, SGP_READ, NULL);
nd_set_link(nd, res ? ERR_PTR(res) : kmap(page));
- return 0;
+ return page;
}
-static void shmem_put_link(struct dentry *dentry, struct nameidata *nd)
+static void shmem_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie)
{
if (!IS_ERR(nd_get_link(nd))) {
- struct page *page;
-
- page = find_get_page(dentry->d_inode->i_mapping, 0);
- if (!page)
- BUG();
+ struct page *page = cookie;
kunmap(page);
mark_page_accessed(page);
page_cache_release(page);
- page_cache_release(page);
}
}