From: Subject: patch ext4-make-sure-all-the-block-allocation-paths-reserve-blocks.patch added to 2.6.27-stable tree Date: Mon, 19 Apr 2010 10:26:57 -0700 Message-ID: <1271698017884@kroah.org> References: <1268699165-17461-4-git-send-email-tytso@mit.edu> Mime-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Cc: , To: aneesh.kumar@linux.vnet.ibm.com, dev@jaysonking.com, gregkh@suse.de, linux-ext4@vger.kernel.org, tytso@mit.edu Return-path: Received: from kroah.org ([198.145.64.141]:48460 "EHLO coco.kroah.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752264Ab0DSR37 (ORCPT ); Mon, 19 Apr 2010 13:29:59 -0400 In-Reply-To: <1268699165-17461-4-git-send-email-tytso@mit.edu> Sender: linux-ext4-owner@vger.kernel.org List-ID: This is a note to let you know that we have just queued up the patch titled Subject: ext4: Make sure all the block allocation paths reserve blocks to the 2.6.27-stable tree. Its filename is ext4-make-sure-all-the-block-allocation-paths-reserve-blocks.patch A git repo of this tree can be found at http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary >From tytso@mit.edu Mon Apr 19 10:20:41 2010 From: Aneesh Kumar K.V Date: Mon, 15 Mar 2010 20:25:57 -0400 Subject: ext4: Make sure all the block allocation paths reserve blocks To: stable@kernel.org Cc: Ext4 Developers List , "Theodore Ts'o" , "Jayson R. King" , "Aneesh Kumar K.V" Message-ID: <1268699165-17461-4-git-send-email-tytso@mit.edu> From: Aneesh Kumar K.V commit a30d542a0035b886ffaafd0057ced0a2b28c3a4f upstream. With delayed allocation we need to make sure block are reserved before we attempt to allocate them. Otherwise we get block allocation failure (ENOSPC) during writepages which cannot be handled. This would mean silent data loss (We do a printk stating data will be lost). This patch updates the DIO and fallocate code path to do block reservation before block allocation. This is needed to make sure parallel DIO and fallocate request doesn't take block out of delayed reserve space. When free blocks count go below a threshold we switch to a slow patch which looks at other CPU's accumulated percpu counter values. Signed-off-by: Aneesh Kumar K.V Signed-off-by: "Theodore Ts'o" Signed-off-by: Jayson R. King Signed-off-by: Theodore Ts'o Signed-off-by: Greg Kroah-Hartman --- fs/ext4/balloc.c | 58 +++++++++++++++++++++++++++++++++++++++--------------- fs/ext4/ext4.h | 13 ++++++++++++ fs/ext4/inode.c | 5 ---- fs/ext4/mballoc.c | 23 ++++++++++++--------- 4 files changed, 69 insertions(+), 30 deletions(-) --- a/fs/ext4/balloc.c +++ b/fs/ext4/balloc.c @@ -1754,6 +1754,32 @@ out: return ret; } +int ext4_claim_free_blocks(struct ext4_sb_info *sbi, + ext4_fsblk_t nblocks) +{ + s64 free_blocks; + ext4_fsblk_t root_blocks = 0; + struct percpu_counter *fbc = &sbi->s_freeblocks_counter; + + free_blocks = percpu_counter_read(fbc); + + if (!capable(CAP_SYS_RESOURCE) && + sbi->s_resuid != current->fsuid && + (sbi->s_resgid == 0 || !in_group_p(sbi->s_resgid))) + root_blocks = ext4_r_blocks_count(sbi->s_es); + + if (free_blocks - (nblocks + root_blocks) < EXT4_FREEBLOCKS_WATERMARK) + free_blocks = percpu_counter_sum(&sbi->s_freeblocks_counter); + + if (free_blocks < (root_blocks + nblocks)) + /* we don't have free space */ + return -ENOSPC; + + /* reduce fs free blocks counter */ + percpu_counter_sub(fbc, nblocks); + return 0; +} + /** * ext4_has_free_blocks() * @sbi: in-core super block structure. @@ -1775,18 +1801,17 @@ ext4_fsblk_t ext4_has_free_blocks(struct sbi->s_resuid != current->fsuid && (sbi->s_resgid == 0 || !in_group_p(sbi->s_resgid))) root_blocks = ext4_r_blocks_count(sbi->s_es); -#ifdef CONFIG_SMP - if (free_blocks - root_blocks < FBC_BATCH) - free_blocks = - percpu_counter_sum(&sbi->s_freeblocks_counter); -#endif + + if (free_blocks - (nblocks + root_blocks) < EXT4_FREEBLOCKS_WATERMARK) + free_blocks = percpu_counter_sum_positive(&sbi->s_freeblocks_counter); + if (free_blocks <= root_blocks) /* we don't have free space */ return 0; if (free_blocks - root_blocks < nblocks) return free_blocks - root_blocks; return nblocks; - } +} /** @@ -1865,14 +1890,11 @@ ext4_fsblk_t ext4_old_new_blocks(handle_ /* * With delalloc we already reserved the blocks */ - *count = ext4_has_free_blocks(sbi, *count); - } - if (*count == 0) { - *errp = -ENOSPC; - return 0; /*return with ENOSPC error */ + if (ext4_claim_free_blocks(sbi, *count)) { + *errp = -ENOSPC; + return 0; /*return with ENOSPC error */ + } } - num = *count; - /* * Check quota for allocation of this block. */ @@ -2067,9 +2089,13 @@ allocated: le16_add_cpu(&gdp->bg_free_blocks_count, -num); gdp->bg_checksum = ext4_group_desc_csum(sbi, group_no, gdp); spin_unlock(sb_bgl_lock(sbi, group_no)); - if (!EXT4_I(inode)->i_delalloc_reserved_flag) - percpu_counter_sub(&sbi->s_freeblocks_counter, num); - + if (!EXT4_I(inode)->i_delalloc_reserved_flag && (*count != num)) { + /* + * we allocated less blocks than we + * claimed. Add the difference back. + */ + percpu_counter_add(&sbi->s_freeblocks_counter, *count - num); + } if (sbi->s_log_groups_per_flex) { ext4_group_t flex_group = ext4_flex_group(sbi, group_no); spin_lock(sb_bgl_lock(sbi, flex_group)); --- a/fs/ext4/ext4.h +++ b/fs/ext4/ext4.h @@ -1015,6 +1015,8 @@ extern ext4_fsblk_t ext4_new_blocks(hand unsigned long *count, int *errp); extern ext4_fsblk_t ext4_old_new_blocks(handle_t *handle, struct inode *inode, ext4_fsblk_t goal, unsigned long *count, int *errp); +extern int ext4_claim_free_blocks(struct ext4_sb_info *sbi, + ext4_fsblk_t nblocks); extern ext4_fsblk_t ext4_has_free_blocks(struct ext4_sb_info *sbi, ext4_fsblk_t nblocks); extern void ext4_free_blocks (handle_t *handle, struct inode *inode, @@ -1245,6 +1247,17 @@ do { \ __ext4_std_error((sb), __func__, (errno)); \ } while (0) +#ifdef CONFIG_SMP +/* Each CPU can accumulate FBC_BATCH blocks in their local + * counters. So we need to make sure we have free blocks more + * than FBC_BATCH * nr_cpu_ids. Also add a window of 4 times. + */ +#define EXT4_FREEBLOCKS_WATERMARK (4 * (FBC_BATCH * nr_cpu_ids)) +#else +#define EXT4_FREEBLOCKS_WATERMARK 0 +#endif + + /* * Inodes and files operations */ --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -1564,13 +1564,10 @@ static int ext4_da_reserve_space(struct md_needed = mdblocks - EXT4_I(inode)->i_reserved_meta_blocks; total = md_needed + nrblocks; - if (ext4_has_free_blocks(sbi, total) < total) { + if (ext4_claim_free_blocks(sbi, total)) { spin_unlock(&EXT4_I(inode)->i_block_reservation_lock); return -ENOSPC; } - /* reduce fs free blocks counter */ - percpu_counter_sub(&sbi->s_freeblocks_counter, total); - EXT4_I(inode)->i_reserved_data_blocks += nrblocks; EXT4_I(inode)->i_reserved_meta_blocks = mdblocks; --- a/fs/ext4/mballoc.c +++ b/fs/ext4/mballoc.c @@ -3194,9 +3194,15 @@ ext4_mb_mark_diskspace_used(struct ext4_ * at write_begin() time for delayed allocation * do not double accounting */ - if (!(ac->ac_flags & EXT4_MB_DELALLOC_RESERVED)) - percpu_counter_sub(&sbi->s_freeblocks_counter, - ac->ac_b_ex.fe_len); + if (!(ac->ac_flags & EXT4_MB_DELALLOC_RESERVED) && + ac->ac_o_ex.fe_len != ac->ac_b_ex.fe_len) { + /* + * we allocated less blocks than we calimed + * Add the difference back + */ + percpu_counter_add(&sbi->s_freeblocks_counter, + ac->ac_o_ex.fe_len - ac->ac_b_ex.fe_len); + } if (sbi->s_log_groups_per_flex) { ext4_group_t flex_group = ext4_flex_group(sbi, @@ -4649,14 +4655,11 @@ ext4_fsblk_t ext4_mb_new_blocks(handle_t /* * With delalloc we already reserved the blocks */ - ar->len = ext4_has_free_blocks(sbi, ar->len); - } - - if (ar->len == 0) { - *errp = -ENOSPC; - return 0; + if (ext4_claim_free_blocks(sbi, ar->len)) { + *errp = -ENOSPC; + return 0; + } }