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authorJan Kara <jack@suse.cz>2012-06-12 16:20:37 +0200
committerAl Viro <viro@zeniv.linux.org.uk>2012-07-31 09:45:47 +0400
commit14da9200140f8d722ad1767dfabadebd8b34f2ad (patch)
treeea5d88b091999f7a64af0b9d335d7cad4c79edfb /fs/splice.c
parent5d37e9e6dec65cd21be68ee92de99686213e916b (diff)
downloadop-kernel-dev-14da9200140f8d722ad1767dfabadebd8b34f2ad.zip
op-kernel-dev-14da9200140f8d722ad1767dfabadebd8b34f2ad.tar.gz
fs: Protect write paths by sb_start_write - sb_end_write
There are several entry points which dirty pages in a filesystem. mmap (handled by block_page_mkwrite()), buffered write (handled by __generic_file_aio_write()), splice write (generic_file_splice_write), truncate, and fallocate (these can dirty last partial page - handled inside each filesystem separately). Protect these places with sb_start_write() and sb_end_write(). ->page_mkwrite() calls are particularly complex since they are called with mmap_sem held and thus we cannot use standard sb_start_write() due to lock ordering constraints. We solve the problem by using a special freeze protection sb_start_pagefault() which ranks below mmap_sem. BugLink: https://bugs.launchpad.net/bugs/897421 Tested-by: Kamal Mostafa <kamal@canonical.com> Tested-by: Peter M. Petrakis <peter.petrakis@canonical.com> Tested-by: Dann Frazier <dann.frazier@canonical.com> Tested-by: Massimo Morana <massimo.morana@canonical.com> Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'fs/splice.c')
-rw-r--r--fs/splice.c3
1 files changed, 3 insertions, 0 deletions
diff --git a/fs/splice.c b/fs/splice.c
index 7bf08fa..41514dd 100644
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -996,6 +996,8 @@ generic_file_splice_write(struct pipe_inode_info *pipe, struct file *out,
};
ssize_t ret;
+ sb_start_write(inode->i_sb);
+
pipe_lock(pipe);
splice_from_pipe_begin(&sd);
@@ -1034,6 +1036,7 @@ generic_file_splice_write(struct pipe_inode_info *pipe, struct file *out,
*ppos += ret;
balance_dirty_pages_ratelimited_nr(mapping, nr_pages);
}
+ sb_end_write(inode->i_sb);
return ret;
}
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