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don't put symlink bodies in pagecache into highmem

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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>
This commit is contained in:
Al Viro 2015-11-17 01:07:57 -05:00 committed by Greg Kroah-Hartman
parent 33813d43dd
commit 076e4ab327
7 changed files with 15 additions and 10 deletions
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1
fs/ext4/inode.c
View File

@ -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;

1
fs/ext4/namei.c
View File

@ -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

10
fs/ext4/symlink.c
View File

@ -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);
}

1
fs/f2fs/inode.c
View File

@ -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)) {

5
fs/f2fs/namei.c
View File

@ -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);
}

6
fs/inode.c
View File

@ -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);

1
include/linux/fs.h
View File

@ -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 */