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author | Jan Kara <jack@suse.cz> | 2012-06-12 16:20:37 +0200 |
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committer | Al Viro <viro@zeniv.linux.org.uk> | 2012-07-31 09:45:47 +0400 |
commit | 14da9200140f8d722ad1767dfabadebd8b34f2ad (patch) | |
tree | ea5d88b091999f7a64af0b9d335d7cad4c79edfb /mm/filemap_xip.c | |
parent | 5d37e9e6dec65cd21be68ee92de99686213e916b (diff) | |
download | linux-3.10-14da9200140f8d722ad1767dfabadebd8b34f2ad.tar.gz linux-3.10-14da9200140f8d722ad1767dfabadebd8b34f2ad.tar.bz2 linux-3.10-14da9200140f8d722ad1767dfabadebd8b34f2ad.zip |
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 'mm/filemap_xip.c')
-rw-r--r-- | mm/filemap_xip.c | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/mm/filemap_xip.c b/mm/filemap_xip.c index 80b34ef82df..13e013b1270 100644 --- a/mm/filemap_xip.c +++ b/mm/filemap_xip.c @@ -402,6 +402,8 @@ xip_file_write(struct file *filp, const char __user *buf, size_t len, loff_t pos; ssize_t ret; + sb_start_write(inode->i_sb); + mutex_lock(&inode->i_mutex); if (!access_ok(VERIFY_READ, buf, len)) { @@ -412,8 +414,6 @@ xip_file_write(struct file *filp, const char __user *buf, size_t len, pos = *ppos; count = len; - vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE); - /* We can write back this queue in page reclaim */ current->backing_dev_info = mapping->backing_dev_info; @@ -437,6 +437,7 @@ xip_file_write(struct file *filp, const char __user *buf, size_t len, current->backing_dev_info = NULL; out_up: mutex_unlock(&inode->i_mutex); + sb_end_write(inode->i_sb); return ret; } EXPORT_SYMBOL_GPL(xip_file_write); |