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| author | Al Viro <viro@zeniv.linux.org.uk> | 2016-01-14 17:52:59 -0500 |
|---|---|---|
| committer | Al Viro <viro@zeniv.linux.org.uk> | 2016-01-14 17:56:54 -0500 |
| commit | e8ecde25f5e08f89b61d86c32bbb56b405e90c32 (patch) | |
| tree | 826e424c86cd079b845ad497bd8c9867b490524f /Documentation | |
| parent | 60b7eca1dc2ec066916b3b7ac6ad89bea13cb9af (diff) | |
| download | linux-e8ecde25f5e08f89b61d86c32bbb56b405e90c32.tar.gz | |
Make sure that highmem pages are not added to symlink page cache
inode_nohighmem() is sufficient to make sure that page_get_link() won't try to allocate a highmem page. Moreover, it is sufficient to make sure that page_symlink/__page_symlink won't do the same thing. However, any filesystem that manually preseeds the symlink's page cache upon symlink(2) needs to make sure that the page it inserts there won't be a highmem one. Fortunately, only nfs and shmem have run afoul of that... Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/filesystems/porting | 6 |
1 files changed, 5 insertions, 1 deletions
diff --git a/Documentation/filesystems/porting b/Documentation/filesystems/porting index 0f88e6020487..f1b87d8aa2da 100644 --- a/Documentation/filesystems/porting +++ b/Documentation/filesystems/porting @@ -508,7 +508,11 @@ in your dentry operations instead. [mandatory] any symlink that might use page_follow_link_light/page_put_link() must have inode_nohighmem(inode) called before anything might start playing with - its pagecache. + its pagecache. No highmem pages should end up in the pagecache of such + symlinks. That includes any preseeding that might be done during symlink + creation. __page_symlink() will honour the mapping gfp flags, so once + you've done inode_nohighmem() it's safe to use, but if you allocate and + insert the page manually, make sure to use the right gfp flags. -- [mandatory] ->follow_link() is replaced with ->get_link(); same API, except that |