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Btrfs: add missing read locks in backref.c
iref_to_path and iterate_irefs both increment the eb's refcount to use it after releasing the path. Both depend on consistent data remaining in the extent buffer and need a read lock to protect it. Signed-off-by: Jan Schmidt <list.btrfs@jan-o-sch.net>
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commit
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1 changed files with 15 additions and 2 deletions
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@ -22,6 +22,7 @@
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#include "ulist.h"
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#include "transaction.h"
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#include "delayed-ref.h"
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#include "locking.h"
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/*
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* this structure records all encountered refs on the way up to the root
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@ -893,18 +894,22 @@ static char *iref_to_path(struct btrfs_root *fs_root, struct btrfs_path *path,
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s64 bytes_left = size - 1;
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struct extent_buffer *eb = eb_in;
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struct btrfs_key found_key;
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int leave_spinning = path->leave_spinning;
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if (bytes_left >= 0)
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dest[bytes_left] = '\0';
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path->leave_spinning = 1;
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while (1) {
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len = btrfs_inode_ref_name_len(eb, iref);
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bytes_left -= len;
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if (bytes_left >= 0)
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read_extent_buffer(eb, dest + bytes_left,
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(unsigned long)(iref + 1), len);
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if (eb != eb_in)
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if (eb != eb_in) {
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btrfs_tree_read_unlock_blocking(eb);
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free_extent_buffer(eb);
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}
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ret = inode_ref_info(parent, 0, fs_root, path, &found_key);
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if (ret > 0)
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ret = -ENOENT;
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@ -919,8 +924,11 @@ static char *iref_to_path(struct btrfs_root *fs_root, struct btrfs_path *path,
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slot = path->slots[0];
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eb = path->nodes[0];
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/* make sure we can use eb after releasing the path */
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if (eb != eb_in)
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if (eb != eb_in) {
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atomic_inc(&eb->refs);
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btrfs_tree_read_lock(eb);
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btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK);
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}
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btrfs_release_path(path);
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iref = btrfs_item_ptr(eb, slot, struct btrfs_inode_ref);
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@ -931,6 +939,7 @@ static char *iref_to_path(struct btrfs_root *fs_root, struct btrfs_path *path,
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}
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btrfs_release_path(path);
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path->leave_spinning = leave_spinning;
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if (ret)
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return ERR_PTR(ret);
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@ -1260,6 +1269,7 @@ static int iterate_irefs(u64 inum, struct btrfs_root *fs_root,
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struct btrfs_key found_key;
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while (!ret) {
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path->leave_spinning = 1;
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ret = inode_ref_info(inum, parent ? parent+1 : 0, fs_root, path,
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&found_key);
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if (ret < 0)
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@ -1275,6 +1285,8 @@ static int iterate_irefs(u64 inum, struct btrfs_root *fs_root,
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eb = path->nodes[0];
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/* make sure we can use eb after releasing the path */
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atomic_inc(&eb->refs);
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btrfs_tree_read_lock(eb);
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btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK);
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btrfs_release_path(path);
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item = btrfs_item_nr(eb, slot);
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@ -1293,6 +1305,7 @@ static int iterate_irefs(u64 inum, struct btrfs_root *fs_root,
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len = sizeof(*iref) + name_len;
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iref = (struct btrfs_inode_ref *)((char *)iref + len);
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}
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btrfs_tree_read_unlock_blocking(eb);
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free_extent_buffer(eb);
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}
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