don't put symlink bodies in pagecache into highmem

commit 21fc61c73c3903c4c312d0802da01ec2b323d174 upstream.

kmap() in page_follow_link_light() needed to go - allowing to hold
an arbitrary number of kmaps for long is a great way to deadlocking
the system.

new helper (inode_nohighmem(inode)) needs to be used for pagecache
symlinks inodes; done for all in-tree cases.  page_follow_link_light()
instrumented to yell about anything missed.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Jin Qian <jinqian@google.com>
Signed-off-by: Jin Qian <jinqian@android.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 4df1cb19a243efb710bc679a2870dc1deaab0be4..f0cabc8c96cb5a82072944eb7936d3e9f31a1310 100644 (file)
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -4417,6 +4417,7 @@ struct inode *ext4_iget(struct super_block *sb, unsigned long ino)
                        inode->i_op = &ext4_symlink_inode_operations;
                        ext4_set_aops(inode);
                }
+               inode_nohighmem(inode);
        } else if (S_ISCHR(inode->i_mode) || S_ISBLK(inode->i_mode) ||
              S_ISFIFO(inode->i_mode) || S_ISSOCK(inode->i_mode)) {
                inode->i_op = &ext4_special_inode_operations;

diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
index 4c36dca486cc1bed8d07cece9325cc6eddfc80d0..32960b3ecd4fb0d35dce4b64a656ed4988d0c249 100644 (file)
--- a/fs/ext4/namei.c
+++ b/fs/ext4/namei.c
@@ -3151,6 +3151,7 @@ static int ext4_symlink(struct inode *dir,
        if ((disk_link.len > EXT4_N_BLOCKS * 4)) {
                if (!encryption_required)
                        inode->i_op = &ext4_symlink_inode_operations;
+               inode_nohighmem(inode);
                ext4_set_aops(inode);
                /*
                 * We cannot call page_symlink() with transaction started

diff --git a/fs/ext4/symlink.c b/fs/ext4/symlink.c
index e8e7af62ac95fc4e5268c32df1bc496a337202a7..287c3980fa0bca5d9f6a9779c5d08bea338defda 100644 (file)
--- a/fs/ext4/symlink.c
+++ b/fs/ext4/symlink.c
@@ -45,7 +45,7 @@ static const char *ext4_encrypted_follow_link(struct dentry *dentry, void **cook
                cpage = read_mapping_page(inode->i_mapping, 0, NULL);
                if (IS_ERR(cpage))
                        return ERR_CAST(cpage);
-               caddr = kmap(cpage);
+               caddr = page_address(cpage);
                caddr[size] = 0;
        }
 
@@ -75,16 +75,12 @@ static const char *ext4_encrypted_follow_link(struct dentry *dentry, void **cook
        /* Null-terminate the name */
        if (res <= plen)
                paddr[res] = '\0';
-       if (cpage) {
-               kunmap(cpage);
+       if (cpage)
                page_cache_release(cpage);
-       }
        return *cookie = paddr;
 errout:
-       if (cpage) {
-               kunmap(cpage);
+       if (cpage)
                page_cache_release(cpage);
-       }
        kfree(paddr);
        return ERR_PTR(res);
 }

diff --git a/fs/f2fs/inode.c b/fs/f2fs/inode.c
index 97e20decacb4e17677fc3c43cfb5d45a6ab290bc..5528801a5baf3a13a75ffd16c831c1d7b1a650f4 100644 (file)
--- a/fs/f2fs/inode.c
+++ b/fs/f2fs/inode.c
@@ -202,6 +202,7 @@ make_now:
                        inode->i_op = &f2fs_encrypted_symlink_inode_operations;
                else
                        inode->i_op = &f2fs_symlink_inode_operations;
+               inode_nohighmem(inode);
                inode->i_mapping->a_ops = &f2fs_dblock_aops;
        } else if (S_ISCHR(inode->i_mode) || S_ISBLK(inode->i_mode) ||
                        S_ISFIFO(inode->i_mode) || S_ISSOCK(inode->i_mode)) {

diff --git a/fs/f2fs/namei.c b/fs/f2fs/namei.c
index 2c32110f9fc082408b318cac2142602ab7888a9e..484df6850747c82314155652474001060b0f4517 100644 (file)
--- a/fs/f2fs/namei.c
+++ b/fs/f2fs/namei.c
@@ -351,6 +351,7 @@ static int f2fs_symlink(struct inode *dir, struct dentry *dentry,
                inode->i_op = &f2fs_encrypted_symlink_inode_operations;
        else
                inode->i_op = &f2fs_symlink_inode_operations;
+       inode_nohighmem(inode);
        inode->i_mapping->a_ops = &f2fs_dblock_aops;
 
        f2fs_lock_op(sbi);
@@ -942,7 +943,7 @@ static const char *f2fs_encrypted_follow_link(struct dentry *dentry, void **cook
        cpage = read_mapping_page(inode->i_mapping, 0, NULL);
        if (IS_ERR(cpage))
                return ERR_CAST(cpage);
-       caddr = kmap(cpage);
+       caddr = page_address(cpage);
        caddr[size] = 0;
 
        /* Symlink is encrypted */
@@ -982,13 +983,11 @@ static const char *f2fs_encrypted_follow_link(struct dentry *dentry, void **cook
        /* Null-terminate the name */
        paddr[res] = '\0';
 
-       kunmap(cpage);
        page_cache_release(cpage);
        return *cookie = paddr;
 errout:
        kfree(cstr.name);
        f2fs_fname_crypto_free_buffer(&pstr);
-       kunmap(cpage);
        page_cache_release(cpage);
        return ERR_PTR(res);
 }

diff --git a/fs/inode.c b/fs/inode.c
index b0edef500590c3e49cd5f632640add63426a39d5..b95615f3fc5070165dfd771740cfc653bcc4a4b4 100644 (file)
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -2028,3 +2028,9 @@ void inode_set_flags(struct inode *inode, unsigned int flags,
                                  new_flags) != old_flags));
 }
 EXPORT_SYMBOL(inode_set_flags);
+
+void inode_nohighmem(struct inode *inode)
+{
+       mapping_set_gfp_mask(inode->i_mapping, GFP_USER);
+}
+EXPORT_SYMBOL(inode_nohighmem);

diff --git a/include/linux/fs.h b/include/linux/fs.h
index c8decb7075d65728fe816cdceec30e38e25dda37..f746a59fcc888b49d426766e9c65e3e7e17a6562 100644 (file)
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -3066,5 +3066,6 @@ static inline bool dir_relax(struct inode *inode)
 }
 
 extern bool path_noexec(const struct path *path);
+extern void inode_nohighmem(struct inode *inode);
 
 #endif /* _LINUX_FS_H */