forked from luck/tmp_suning_uos_patched
487caeef9f
During truncate we are sometimes forced to start a new transaction as the amount of blocks to be journaled is both quite large and hard to predict. So far we restarted a transaction while holding i_data_sem and that violates lock ordering because i_data_sem ranks below a transaction start (and it can lead to a real deadlock with ext4_get_blocks() mapping blocks in some page while having a transaction open). We fix the problem by dropping the i_data_sem before restarting the transaction and acquire it afterwards. It's slightly subtle that this works: 1) By the time ext4_truncate() is called, all the page cache for the truncated part of the file is dropped so get_block() should not be called on it (we only have to invalidate extent cache after we reacquire i_data_sem because some extent from not-truncated part could extend also into the part we are going to truncate). 2) Writes, migrate or defrag hold i_mutex so they are stopped for all the time of the truncate. This bug has been found and analyzed by Theodore Tso <tytso@mit.edu>. Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu> |
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| .. | ||
| acl.c | ||
| acl.h | ||
| balloc.c | ||
| bitmap.c | ||
| block_validity.c | ||
| dir.c | ||
| ext4_extents.h | ||
| ext4_jbd2.c | ||
| ext4_jbd2.h | ||
| ext4.h | ||
| extents.c | ||
| file.c | ||
| fsync.c | ||
| hash.c | ||
| ialloc.c | ||
| inode.c | ||
| ioctl.c | ||
| Kconfig | ||
| Makefile | ||
| mballoc.c | ||
| mballoc.h | ||
| migrate.c | ||
| move_extent.c | ||
| namei.c | ||
| resize.c | ||
| super.c | ||
| symlink.c | ||
| xattr_security.c | ||
| xattr_trusted.c | ||
| xattr_user.c | ||
| xattr.c | ||
| xattr.h | ||