lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
Open Source and information security mailing list archives
| ||
|
Message-ID: <4F98B9A7.8060209@gmail.com> Date: Thu, 26 Apr 2012 10:57:43 +0800 From: Miao Xie <miaoxie1984@...il.com> To: Alexander Viro <viro@...iv.linux.org.uk> CC: Christoph Hellwig <hch@...radead.org>, Linux FSDevel <linux-fsdevel@...r.kernel.org>, Linux Btrfs <linux-btrfs@...r.kernel.org>, miaox@...fujitsu.com, Kamal Mostafa <kamal@...onical.com>, Linux Ext4 <linux-ext4@...r.kernel.org> Subject: [PATCH 1/4] vfs: introduce try_to_writeback_inodes_sb(_nr) writeback_inodes_sb(_nr) grabs s_umount lock when it want to start writeback, it may bring us deadlock problem when doing umount. So we introduce new functions -- try_to_writeback_inodes_sb(_nr) -- which use down_read_trylock() instead of down_read() to avoid that deadlock problem. This idea came from Christoph Hellwig. Some code is from the patch of Kamal Mostafa. Signed-off-by: Miao Xie <miaox@...fujitsu.com> --- fs/fs-writeback.c | 39 +++++++++++++++++++++++++++++++++++++++ include/linux/writeback.h | 3 +++ 2 files changed, 42 insertions(+), 0 deletions(-) diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c index 539f36c..b0c35c3 100644 --- a/fs/fs-writeback.c +++ b/fs/fs-writeback.c @@ -1291,6 +1291,45 @@ int writeback_inodes_sb_nr_if_idle(struct super_block *sb, EXPORT_SYMBOL(writeback_inodes_sb_nr_if_idle); /** + * try_to_writeback_inodes_sb_nr - try to start writeback if none underway + * @sb: the superblock + * @nr: the number of pages to write + * @reason: the reason of writeback + * + * Invoke writeback_inodes_sb_nr if no writeback is currently underway. + * Returns 1 if writeback was started, 0 if not. + */ +int try_to_writeback_inodes_sb_nr(struct super_block *sb, + unsigned long nr, + enum wb_reason reason) +{ + if (writeback_in_progress(sb->s_bdi)) + return 1; + + if (!down_read_trylock(&sb->s_umount)) + return 0; + + writeback_inodes_sb_nr(sb, nr, reason); + up_read(&sb->s_umount); + return 1; +} +EXPORT_SYMBOL(try_to_writeback_inodes_sb_nr); + +/** + * try_to_writeback_inodes_sb - try to start writeback if none underway + * @sb: the superblock + * @reason: reason why some writeback work was initiated + * + * Implement by try_to_writeback_inodes_sb_nr() + * Returns 1 if writeback was started, 0 if not. + */ +int try_to_writeback_inodes_sb(struct super_block *sb, enum wb_reason reason) +{ + return try_to_writeback_inodes_sb_nr(sb, get_nr_dirty_pages(), reason); +} +EXPORT_SYMBOL(try_to_writeback_inodes_sb); + +/** * sync_inodes_sb - sync sb inode pages * @sb: the superblock * diff --git a/include/linux/writeback.h b/include/linux/writeback.h index a2b84f5..d8e2a99 100644 --- a/include/linux/writeback.h +++ b/include/linux/writeback.h @@ -89,6 +89,9 @@ void writeback_inodes_sb_nr(struct super_block *, unsigned long nr, int writeback_inodes_sb_if_idle(struct super_block *, enum wb_reason reason); int writeback_inodes_sb_nr_if_idle(struct super_block *, unsigned long nr, enum wb_reason reason); +int try_to_writeback_inodes_sb(struct super_block *, enum wb_reason reason); +int try_to_writeback_inodes_sb_nr(struct super_block *, unsigned long nr, + enum wb_reason reason); void sync_inodes_sb(struct super_block *); long writeback_inodes_wb(struct bdi_writeback *wb, long nr_pages, enum wb_reason reason); -- 1.7.6.5 -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Powered by blists - more mailing lists