| Message ID | 1386670181-2151-1-git-send-email-jack@suse.cz |
|---|---|
| State | Superseded, archived |
| Headers | show |
Please ignore the below patch. It is part of the larger series I've submitted a bit later... Honza On Tue 10-12-13 11:09:41, Jan Kara wrote: > 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> > Signed-off-by: Jan Kara <jack@suse.cz> > --- > fs/ext4/inode.c | 12 ------------ > 1 file changed, 12 deletions(-) > > diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c > index 075763474118..61d49ff22c81 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; > } > -- > 1.8.1.4 >
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index 075763474118..61d49ff22c81 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; }
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> Signed-off-by: Jan Kara <jack@suse.cz> --- fs/ext4/inode.c | 12 ------------ 1 file changed, 12 deletions(-)