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| author |   Theodore Ts'o <tytso@mit.edu> | 2016-04-23 22:50:07 -0400 |
|---|---|---|
| committer | Theodore Ts'o <tytso@mit.edu> | 2016-04-23 22:50:07 -0400 |
| commit | 1f60fbe7274918adb8db2f616e321890730ab7e3 (patch) | |
| tree | 4e41c7a0fd5204cad9e651baa23207bf4dafe256 /fs | |
| parent | Linux 4.6-rc4 (diff) | |
| download | wireguard-linux-1f60fbe7274918adb8db2f616e321890730ab7e3.tar.xz wireguard-linux-1f60fbe7274918adb8db2f616e321890730ab7e3.zip | |
ext4: allow readdir()'s of large empty directories to be interrupted
If a directory has a large number of empty blocks, iterating over all
of them can take a long time, leading to scheduler warnings and users
getting irritated when they can't kill a process in the middle of one
of these long-running readdir operations. Fix this by adding checks to
ext4_readdir() and ext4_htree_fill_tree().
This was reverted earlier due to a typo in the original commit where I
experimented with using signal_pending() instead of
fatal_signal_pending(). The test was in the wrong place if we were
going to return signal_pending() since we would end up returning
duplicant entries. See 9f2394c9be47 for a more detailed explanation.
Added fix as suggested by Linus to check for signal_pending() in
in the filldir() functions.
Reported-by: Benjamin LaHaise <bcrl@kvack.org>
Google-Bug-Id: 27880676
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/compat.c | 4 | ||||
| -rw-r--r-- | fs/ext4/dir.c | 5 | ||||
| -rw-r--r-- | fs/ext4/namei.c | 5 | ||||
| -rw-r--r-- | fs/readdir.c | 4 |
4 files changed, 18 insertions, 0 deletions
diff --git a/fs/compat.c b/fs/compat.c index a71936a3f4cb..f940cb20562f 100644 --- a/fs/compat.c +++ b/fs/compat.c @@ -936,6 +936,8 @@ static int compat_filldir(struct dir_context *ctx, const char *name, int namlen, } dirent = buf->previous; if (dirent) { + if (signal_pending(current)) + return -EINTR; if (__put_user(offset, &dirent->d_off)) goto efault; } @@ -1020,6 +1022,8 @@ static int compat_filldir64(struct dir_context *ctx, const char *name, dirent = buf->previous; if (dirent) { + if (signal_pending(current)) + return -EINTR; if (__put_user_unaligned(offset, &dirent->d_off)) goto efault; } diff --git a/fs/ext4/dir.c b/fs/ext4/dir.c index 561d7308b393..4173bfe21114 100644 --- a/fs/ext4/dir.c +++ b/fs/ext4/dir.c @@ -150,6 +150,11 @@ static int ext4_readdir(struct file *file, struct dir_context *ctx) while (ctx->pos < inode->i_size) { struct ext4_map_blocks map; + if (fatal_signal_pending(current)) { + err = -ERESTARTSYS; + goto errout; + } + cond_resched(); map.m_lblk = ctx->pos >> EXT4_BLOCK_SIZE_BITS(sb); map.m_len = 1; err = ext4_map_blocks(NULL, inode, &map, 0); diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c index 48e4b8907826..c07422d254b6 100644 --- a/fs/ext4/namei.c +++ b/fs/ext4/namei.c @@ -1107,6 +1107,11 @@ int ext4_htree_fill_tree(struct file *dir_file, __u32 start_hash, } while (1) { + if (fatal_signal_pending(current)) { + err = -ERESTARTSYS; + goto errout; + } + cond_resched(); block = dx_get_block(frame->at); ret = htree_dirblock_to_tree(dir_file, dir, block, &hinfo, start_hash, start_minor_hash); diff --git a/fs/readdir.c b/fs/readdir.c index e69ef3b79787..5f2d4bee5a73 100644 --- a/fs/readdir.c +++ b/fs/readdir.c @@ -169,6 +169,8 @@ static int filldir(struct dir_context *ctx, const char *name, int namlen, } dirent = buf->previous; if (dirent) { + if (signal_pending(current)) + return -EINTR; if (__put_user(offset, &dirent->d_off)) goto efault; } @@ -248,6 +250,8 @@ static int filldir64(struct dir_context *ctx, const char *name, int namlen, return -EINVAL; dirent = buf->previous; if (dirent) { + if (signal_pending(current)) + return -EINTR; if (__put_user(offset, &dirent->d_off)) goto efault; } |