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authorJan Kara <jack@suse.cz>2013-12-18 05:44:44 (GMT)
committerTheodore Ts'o <tytso@mit.edu>2013-12-18 05:44:44 (GMT)
commit34cf865d54813aab3497838132fb1bbd293f4054 (patch)
tree1c35c9598e48f8a68ae976bc4ae4ef3374cd8774 /fs/ext4
parenta67c848a8b9aa9e471f9eaadd2cb29cc527462cf (diff)
downloadlinux-34cf865d54813aab3497838132fb1bbd293f4054.tar.xz
ext4: fix deadlock when writing in ENOSPC conditions
Akira-san has been reporting rare deadlocks of his machine when running xfstests test 269 on ext4 filesystem. The problem turned out to be in ext4_da_reserve_metadata() and ext4_da_reserve_space() which called ext4_should_retry_alloc() while holding i_data_sem. Since ext4_should_retry_alloc() can force a transaction commit, this is a lock ordering violation and leads to deadlocks. Fix the problem by just removing the retry loops. These functions should just report ENOSPC to the caller (e.g. ext4_da_write_begin()) and that function must take care of retrying after dropping all necessary locks. Reported-and-tested-by: Akira Fujita <a-fujita@rs.jp.nec.com> Reviewed-by: Zheng Liu <wenqing.lz@taobao.com> Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu> Cc: stable@vger.kernel.org
Diffstat (limited to 'fs/ext4')
-rw-r--r--fs/ext4/inode.c12
1 files changed, 0 insertions, 12 deletions
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 0757634..61d49ff 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -1206,7 +1206,6 @@ static int ext4_journalled_write_end(struct file *file,
*/
static int ext4_da_reserve_metadata(struct inode *inode, ext4_lblk_t lblock)
{
- int retries = 0;
struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
struct ext4_inode_info *ei = EXT4_I(inode);
unsigned int md_needed;
@@ -1218,7 +1217,6 @@ static int ext4_da_reserve_metadata(struct inode *inode, ext4_lblk_t lblock)
* in order to allocate nrblocks
* worse case is one extent per block
*/
-repeat:
spin_lock(&ei->i_block_reservation_lock);
/*
* ext4_calc_metadata_amount() has side effects, which we have
@@ -1238,10 +1236,6 @@ repeat:
ei->i_da_metadata_calc_len = save_len;
ei->i_da_metadata_calc_last_lblock = save_last_lblock;
spin_unlock(&ei->i_block_reservation_lock);
- if (ext4_should_retry_alloc(inode->i_sb, &retries)) {
- cond_resched();
- goto repeat;
- }
return -ENOSPC;
}
ei->i_reserved_meta_blocks += md_needed;
@@ -1255,7 +1249,6 @@ repeat:
*/
static int ext4_da_reserve_space(struct inode *inode, ext4_lblk_t lblock)
{
- int retries = 0;
struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
struct ext4_inode_info *ei = EXT4_I(inode);
unsigned int md_needed;
@@ -1277,7 +1270,6 @@ static int ext4_da_reserve_space(struct inode *inode, ext4_lblk_t lblock)
* in order to allocate nrblocks
* worse case is one extent per block
*/
-repeat:
spin_lock(&ei->i_block_reservation_lock);
/*
* ext4_calc_metadata_amount() has side effects, which we have
@@ -1297,10 +1289,6 @@ repeat:
ei->i_da_metadata_calc_len = save_len;
ei->i_da_metadata_calc_last_lblock = save_last_lblock;
spin_unlock(&ei->i_block_reservation_lock);
- if (ext4_should_retry_alloc(inode->i_sb, &retries)) {
- cond_resched();
- goto repeat;
- }
dquot_release_reservation_block(inode, EXT4_C2B(sbi, 1));
return -ENOSPC;
}