ext4: Fix the race between read_inode_bitmap() and ext4_new_inode()
We need to make sure we update the inode bitmap and clear EXT4_BG_INODE_UNINIT flag with sb_bgl_lock held, since ext4_read_inode_bitmap() looks at EXT4_BG_INODE_UNINIT to decide whether to initialize the inode bitmap each time it is called. (introduced by commit c806e68f.) ext4_read_inode_bitmap does: spin_lock(sb_bgl_lock(EXT4_SB(sb), block_group)); if (desc->bg_flags & cpu_to_le16(EXT4_BG_INODE_UNINIT)) { ext4_init_inode_bitmap(sb, bh, block_group, desc); and ext4_new_inode does if (!ext4_set_bit_atomic(sb_bgl_lock(sbi, group), ino, inode_bitmap_bh->b_data)) ...... ... spin_lock(sb_bgl_lock(sbi, group)); gdp->bg_flags &= cpu_to_le16(~EXT4_BG_INODE_UNINIT); i.e., on allocation we update the bitmap then we take the sb_bgl_lock and clear the EXT4_BG_INODE_UNINIT flag. What can happen is a parallel ext4_read_inode_bitmap can zero out the bitmap in between the above ext4_set_bit_atomic and spin_lock(sb_bg_lock..) The race results in below user visible errors EXT4-fs error (device sdb1): ext4_free_inode: bit already cleared for inode 168449 EXT4-fs warning (device sdb1): ext4_unlink: Deleting nonexistent file ... EXT4-fs warning (device sdb1): ext4_rmdir: empty directory has too many links ... # ls -al /mnt/tmp/f/p369/d3/d6/d39/db2/dee/d10f/d3f/l71 ls: /mnt/tmp/f/p369/d3/d6/d39/db2/dee/d10f/d3f/l71: Stale NFS file handle Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu> Cc: stable@kernel.org
This commit is contained in:
parent
3300beda52
commit
393418676a
146
fs/ext4/ialloc.c
146
fs/ext4/ialloc.c
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@ -572,6 +572,79 @@ static int find_group_other(struct super_block *sb, struct inode *parent,
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return -1;
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}
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/*
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* claim the inode from the inode bitmap. If the group
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* is uninit we need to take the groups's sb_bgl_lock
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* and clear the uninit flag. The inode bitmap update
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* and group desc uninit flag clear should be done
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* after holding sb_bgl_lock so that ext4_read_inode_bitmap
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* doesn't race with the ext4_claim_inode
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*/
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static int ext4_claim_inode(struct super_block *sb,
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struct buffer_head *inode_bitmap_bh,
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unsigned long ino, ext4_group_t group, int mode)
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{
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int free = 0, retval = 0, count;
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struct ext4_sb_info *sbi = EXT4_SB(sb);
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struct ext4_group_desc *gdp = ext4_get_group_desc(sb, group, NULL);
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spin_lock(sb_bgl_lock(sbi, group));
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if (ext4_set_bit(ino, inode_bitmap_bh->b_data)) {
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/* not a free inode */
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retval = 1;
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goto err_ret;
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}
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ino++;
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if ((group == 0 && ino < EXT4_FIRST_INO(sb)) ||
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ino > EXT4_INODES_PER_GROUP(sb)) {
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spin_unlock(sb_bgl_lock(sbi, group));
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ext4_error(sb, __func__,
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"reserved inode or inode > inodes count - "
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"block_group = %u, inode=%lu", group,
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ino + group * EXT4_INODES_PER_GROUP(sb));
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return 1;
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}
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/* If we didn't allocate from within the initialized part of the inode
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* table then we need to initialize up to this inode. */
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if (EXT4_HAS_RO_COMPAT_FEATURE(sb, EXT4_FEATURE_RO_COMPAT_GDT_CSUM)) {
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if (gdp->bg_flags & cpu_to_le16(EXT4_BG_INODE_UNINIT)) {
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gdp->bg_flags &= cpu_to_le16(~EXT4_BG_INODE_UNINIT);
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/* When marking the block group with
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* ~EXT4_BG_INODE_UNINIT we don't want to depend
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* on the value of bg_itable_unused even though
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* mke2fs could have initialized the same for us.
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* Instead we calculated the value below
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*/
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free = 0;
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} else {
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free = EXT4_INODES_PER_GROUP(sb) -
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ext4_itable_unused_count(sb, gdp);
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}
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/*
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* Check the relative inode number against the last used
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* relative inode number in this group. if it is greater
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* we need to update the bg_itable_unused count
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*
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*/
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if (ino > free)
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ext4_itable_unused_set(sb, gdp,
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(EXT4_INODES_PER_GROUP(sb) - ino));
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}
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count = ext4_free_inodes_count(sb, gdp) - 1;
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ext4_free_inodes_set(sb, gdp, count);
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if (S_ISDIR(mode)) {
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count = ext4_used_dirs_count(sb, gdp) + 1;
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ext4_used_dirs_set(sb, gdp, count);
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}
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gdp->bg_checksum = ext4_group_desc_csum(sbi, group, gdp);
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err_ret:
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spin_unlock(sb_bgl_lock(sbi, group));
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return retval;
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}
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/*
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* There are two policies for allocating an inode. If the new inode is
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* a directory, then a forward search is made for a block group with both
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@ -594,7 +667,7 @@ struct inode *ext4_new_inode(handle_t *handle, struct inode *dir, int mode)
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struct ext4_super_block *es;
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struct ext4_inode_info *ei;
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struct ext4_sb_info *sbi;
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int ret2, err = 0, count;
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int ret2, err = 0;
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struct inode *ret;
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ext4_group_t i;
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int free = 0;
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@ -658,8 +731,13 @@ repeat_in_this_group:
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if (err)
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goto fail;
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if (!ext4_set_bit_atomic(sb_bgl_lock(sbi, group),
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ino, inode_bitmap_bh->b_data)) {
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BUFFER_TRACE(group_desc_bh, "get_write_access");
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err = ext4_journal_get_write_access(handle,
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group_desc_bh);
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if (err)
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goto fail;
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if (!ext4_claim_inode(sb, inode_bitmap_bh,
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ino, group, mode)) {
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/* we won it */
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BUFFER_TRACE(inode_bitmap_bh,
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"call ext4_handle_dirty_metadata");
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@ -668,10 +746,13 @@ repeat_in_this_group:
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inode_bitmap_bh);
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if (err)
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goto fail;
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/* zero bit is inode number 1*/
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ino++;
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goto got;
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}
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/* we lost it */
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ext4_handle_release_buffer(handle, inode_bitmap_bh);
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ext4_handle_release_buffer(handle, group_desc_bh);
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if (++ino < EXT4_INODES_PER_GROUP(sb))
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goto repeat_in_this_group;
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@ -691,22 +772,6 @@ repeat_in_this_group:
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goto out;
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got:
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ino++;
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if ((group == 0 && ino < EXT4_FIRST_INO(sb)) ||
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ino > EXT4_INODES_PER_GROUP(sb)) {
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ext4_error(sb, __func__,
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"reserved inode or inode > inodes count - "
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"block_group = %u, inode=%lu", group,
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ino + group * EXT4_INODES_PER_GROUP(sb));
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err = -EIO;
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goto fail;
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}
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BUFFER_TRACE(group_desc_bh, "get_write_access");
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err = ext4_journal_get_write_access(handle, group_desc_bh);
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if (err)
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goto fail;
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/* We may have to initialize the block bitmap if it isn't already */
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if (EXT4_HAS_RO_COMPAT_FEATURE(sb, EXT4_FEATURE_RO_COMPAT_GDT_CSUM) &&
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gdp->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT)) {
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@ -743,49 +808,10 @@ got:
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if (err)
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goto fail;
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}
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spin_lock(sb_bgl_lock(sbi, group));
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/* If we didn't allocate from within the initialized part of the inode
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* table then we need to initialize up to this inode. */
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if (EXT4_HAS_RO_COMPAT_FEATURE(sb, EXT4_FEATURE_RO_COMPAT_GDT_CSUM)) {
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if (gdp->bg_flags & cpu_to_le16(EXT4_BG_INODE_UNINIT)) {
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gdp->bg_flags &= cpu_to_le16(~EXT4_BG_INODE_UNINIT);
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/* When marking the block group with
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* ~EXT4_BG_INODE_UNINIT we don't want to depend
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* on the value of bg_itable_unused even though
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* mke2fs could have initialized the same for us.
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* Instead we calculated the value below
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*/
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free = 0;
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} else {
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free = EXT4_INODES_PER_GROUP(sb) -
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ext4_itable_unused_count(sb, gdp);
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}
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/*
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* Check the relative inode number against the last used
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* relative inode number in this group. if it is greater
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* we need to update the bg_itable_unused count
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*
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*/
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if (ino > free)
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ext4_itable_unused_set(sb, gdp,
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(EXT4_INODES_PER_GROUP(sb) - ino));
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}
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count = ext4_free_inodes_count(sb, gdp) - 1;
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ext4_free_inodes_set(sb, gdp, count);
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if (S_ISDIR(mode)) {
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count = ext4_used_dirs_count(sb, gdp) + 1;
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ext4_used_dirs_set(sb, gdp, count);
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}
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gdp->bg_checksum = ext4_group_desc_csum(sbi, group, gdp);
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spin_unlock(sb_bgl_lock(sbi, group));
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BUFFER_TRACE(group_desc_bh, "call ext4_handle_dirty_metadata");
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err = ext4_handle_dirty_metadata(handle, NULL, group_desc_bh);
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if (err) goto fail;
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if (err)
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goto fail;
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percpu_counter_dec(&sbi->s_freeinodes_counter);
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if (S_ISDIR(mode))
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